Modular radio frequency aperture

ABSTRACT

An air interface plane (AIP) of a radio frequency (RF) aperture includes: a circuit board having a first side and a second side opposite the first side; and a matrix of tapered elements arranged on the first side of the circuit board and secured to the circuit board, the matrix of tapered elements cooperating to at least one of receive or transmit an over-the-air RF signal. Suitably, each tapered element of the matrix has: a central hub extending along a longitudinal axis from a hub base which is proximate to the first side of the circuit board to an apex of the tapered element which is distal from the first side of the first circuit board; and a plurality of arms extending from the central hub at the apex of the tapered element, each of the plurality of arms including a first portion that projects the arm radially away from the longitudinal axis and a second portion that projects the arm longitudinally toward the first side of the circuit board.

BACKGROUND

The following relates to the radio frequency (RF) arts, RF transmitterarts, RF receiver arts, RF transceiver arts, broadband RF transmitter,receiver, and/or transceiver arts, RF communications arts, and relatedarts.

Steinbrecher, U.S. Pat. No. 7,420,522 titled “Electromagnetic RadiationInterface System and Method” discloses a broadband RF aperture asfollows: “An electromagnetic radiation interface is provided that issuitable for use with radio wave frequencies. A surface is provided witha plurality of metallic conical bristles. A corresponding plurality oftermination sections are provided so that each bristle is terminatedwith a termination section. The termination section may comprise anelectrical resistance for capturing substantially all theelectromagnetic wave energy received by each respective bristle tothereby prevent reflections from the surface of the interface. Eachtermination section may also comprise an analog to digital converter forconverting the energy from each bristle to a digital word. The bristlesmay be mounted on a ground plane having a plurality of holestherethrough. A plurality of coaxial transmission lines may extendthrough the ground plane for interconnecting the plurality of bristlesto the plurality of termination sections.”

Certain improvements are disclosed herein.

BRIEF SUMMARY

In accordance with some non-limiting illustrative embodiments disclosedherein, an air interface plane (AIP) of a radio frequency (RF) apertureincludes: a circuit board having a first side and a second side oppositethe first side; and a matrix of tapered elements arranged on the firstside of the circuit board and secured to the circuit board, the matrixof tapered elements cooperating to at least one of receive or transmitan over-the-air RF signal. Suitably, each tapered element of the matrixincludes: a central hub extending along a longitudinal axis defining anapex of the tapered element which is distal from the first side of thefirst circuit board; and a plurality of arms extending from the centralhub at the apex of the tapered element, each of the plurality of armsincluding a first portion that projects the arm radially away from alongitudinal axis perpendicular to the board and passing through theapex and a second portion that projects the arm longitudinally towardthe first side of the circuit board

In accordance with some non-limiting illustrative embodiments disclosedherein, a radio frequency (RF) aperture includes:

-   -   a digital personality circuit board (DPB);    -   a transmit section including:        -   a first air interface plane (AIP) having:            -   a first AIP circuit board with a first side and a second                side opposite the first side; and            -   a first matrix of tapered elements arranged on the first                side of the first AIP circuit board and secured to the                first AIP circuit board, neighboring tapered elements of                the first matrix defining a transmission pixel within                the first matrix and the first matrix of tapered                elements cooperating to selectively transmit                over-the-air RF signals;            -   a first conditioning circuit board electrically                connected to the first AIP circuit board, the first                conditioning circuit board being selectively operative                to at least one of condition or amplify individual                transmit signals provided to each transmission pixel of                the first matrix;            -   a splitting circuit board electrically connected to the                first conditioning circuit board, the splitting circuit                board being selectively operative to receive a modulated                transmit signal from the DPB and divide the received                modulated transmit signal into individual transmit                signals for each transmission pixel of the first matrix;                and            -   a power supply circuit board electrically connected at                least to the first conditioning circuit board and the                splitting circuit board, the power supply circuit board                selectively providing electrical power to operate at                least the first conditioning circuit board and the                splitting circuit board; and    -   a receive section including:        -   a second AIP having:            -   a second AIP circuit board with a first side and a                second side opposite the first side; and            -   a second matrix of tapered elements arranged on the                first side of the second AIP circuit board and secured                to the second AIP circuit board, neighboring tapered                elements of the second matrix defining a reception pixel                within the second matrix and the second matrix of                tapered elements cooperating to selectively receive                over-the-air RF signals;            -   a second conditioning circuit board electrically                connected to the second AIP circuit board, the second                conditioning circuit board being selectively operative                to at least one of condition or amplify individual                receive signals received by each reception pixel of the                second matrix; and            -   a combining circuit board electrically connected to the                second conditioning circuit board, the combining circuit                board being selectively operative to combine individual                receive signals from each reception pixel of the second                matrix into a combined receive signal and provide the                combined receive signal to the DPB;    -   wherein the first and second AIP circuit boards, the first and        second conditioning circuit boards, the splitting and combining        circuit boards, the power supply circuit board and the DPB are        modularly interconnected such that a given one of the circuit        boards may be selectively removed and replaced without removing        and replacing another one of the circuit boards.

In accordance with some non-limiting illustrative embodiments disclosedherein, an RF aperture includes a digital personality circuit board(DPB) and an air interface plane (AIP) having: an AIP circuit board witha first side and a second side opposite the first side; a matrix oftapered elements arranged on the first side of the AIP circuit board andsecured to the AIP circuit board, neighboring tapered elements of thematrix defining a pixel within the matrix and the matrix of taperedelements cooperating to selectively at least one of transmit or receiveover-the-air RF signals; a conditioning circuit board electricallyconnected to the AIP circuit board, the conditioning circuit board beingselectively operative to at least one of condition or amplify individualsignals for each pixel of the matrix; a splitting/combining circuitboard electrically connected to the conditioning circuit board, thesplitting/combining circuit board being selectively operative to atleast one of (a) receive a modulated transmit signal from the DPB anddivide the received modulated transmit signal into individual transmitsignals for each pixel of the first matrix, or (b) combine individualreceive signals from each pixel of the matrix into a combined receivesignal and provide the combined receive signal to the DPB; and a powersupply circuit board electrically connected to the conditioning circuitboard and the splitting/combining circuit board, the power supplycircuit board selectively providing electrical power to operate theconditioning circuit board and the splitting/combining circuit board.The aperture further includes: a housing defining an interior cavitycontaining the DPB, AIP, conditioning circuit board, splitting combiningcircuit board and power supply circuit board, such that the AIP circuitboard, the conditioning circuit board, the splitting/combining circuitboard, the power supply circuit board and the DPB are arranged in astack one over another; and a cooling assembly. Suitably, the coolingassembly includes: a fan operative to draw air out of the housingthrough an exhaust vent in a first wall of the housing; a first heatsink within the stack positioned between the conditioning circuit boardand the power supply circuit board; a second heat sink within the stackposition between the power supply circuit board and thesplitting/combining circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS

Any quantitative dimensions shown in the drawing are to be understood asnon-limiting illustrative examples. Unless otherwise indicated, thedrawings are not to scale; if any aspect of the drawings is indicated asbeing to scale, the illustrated scale is to be understood asnon-limiting illustrative example.

FIGS. 1 and 2 diagrammatically illustrate front and side-sectionalviews, respectively, of an illustrative RF aperture implemented as adifferential segmented aperture (DSA).

FIG. 3 diagrammatically shows a block diagram of a single QUADsubassembly of the DSA of FIGS. 1-4 .

FIG. 4 diagrammatically illustrates a front view of the interfaceprinted circuit board (i-PCB) of the DSA of FIGS. 1-3 including vias andmounting holes and diagrammatically indicated locations of baluns andresistor pads.

FIG. 5 diagrammatically illustrates a rear view of the enclosure of theDSA of FIGS. 1-4 including diagrammatically indicated RF connections,control, and power connectors.

FIG. 6 diagrammatically illustrates a side sectional view of anembodiment of the electrically conductive tapered projections, alongwith a diagrammatic representation of the connection of the balancedport of a chip balun between two adjacent electrically conductivetapered projections.

FIGS. 7-10 diagrammatically illustrate additional embodiments of theelectrically conductive tapered projections.

FIGS. 11 and 12 show embodiments in which the electrically conductivetapered projections of the RF aperture are hollow and in which one ormore electronic components are disposed inside the hollow electricallyconductive tapered projections.

FIG. 13 diagrammatically illustrates an exploded view of anotherillustrative RF aperture assembly.

FIGS. 14-17 diagrammatically show some illustrative layouts ofelectrically conductive tapered projections over the area of the RFaperture.

FIGS. 18-24 show side sectional view of RF aperture embodimentsemploying dielectric filling material disposed between neighboringelectrically conductive tapered projections to tune the RF captureperformance for transmit and/or receive operations.

FIG. 25 shows another illustrative RF aperture assembly.

FIG. 26 shows an RF aperture comprising electrically conductive taperedprojections disposed on a curved (e.g. radial) surface.

FIG. 27 diagrammatically shows a network employing DSAs.

FIG. 28 diagrammatically shows a processing node suitable employed inconjunction with the embodiment of FIG. 25 .

FIGS. 29-36 illustrate embodiments of electrically conductive taperedprojections which are solid projections.

FIGS. 37-39 illustrate some alternative faceted electrically conductivetapered projection geometries.

FIGS. 40-41 illustrate an embodiment of an electrically conductivetapered projection which is hollow.

FIGS. 42-46 illustrate an embodiment of an electrically conductivetapered projection which includes a dielectric structure and taperedplates.

FIGS. 47-49 illustrate mounting of electrically conductive taperedprojections of FIGS. 42-46 on an interface board.

FIGS. 50-54 illustrate embodiments of electrically conductive taperedprojections constructed by folding a cut-out of sheet metal.

FIG. 55 illustrates an embodiment of electrically conductive taperedprojections constructed by punching sheet metal into a radome definingtapered projection forms.

FIG. 56 illustrates potential RF interference in a DSA due to aninterface board with a ground plane.

FIG. 57 illustrates an embodiment employing standoffs to mitigate thepotential RF interference described with reference to FIG. 56 .

FIGS. 58-63 illustrate embodiments employing RF circuitry comprisingperpendicular printed circuit boards (PCBs) to mitigate the potential RFinterference described with reference to FIG. 56 .

FIG. 64 illustrates an exploded view of a DSA including a radome andperpendicular PCBs as described with reference to FIGS. 58-63 .

FIG. 65 illustrates the five-sided housing or enclosure of the DSAembodiment of FIG. 64 .

FIGS. 66-81 illustrate various embodiments of RF circuitry suitably usedwith DSA embodiments disclosed herein.

FIG. 82 is a diagrammatic illustration showing a perspective view of yetanother embodiment of an RF aperture provisioned with a plurality ofelectrically conductive tapered projections in accordance with somesuitable embodiments disclosed herein.

FIG. 83 is a diagrammatic illustration showing a cross section view ofthe RF aperture shown in FIG. 82 taken along section line A-A.

FIG. 84 is a diagrammatic illustration showing a partial perspectiveview of the RF aperture shown in FIG. 82 .

FIG. 85 is a diagrammatic illustration showing an exploded view of theRF aperture as depicted in FIG. 84 .

FIG. 86 is a diagrammatic illustration showing a perspective view of aportion of a cooling assembly in accordance with some embodiments of theaperture shown in FIG. 82 .

FIG. 87 is a diagrammatic illustration showing an end view of a portionof a cooling assembly in accordance with some embodiments of theaperture shown in FIG. 82

FIG. 88 is a diagrammatic illustration showing a perspective view of aheat sink plate of a cooling assembly in accordance with someembodiments of the aperture shown in FIG. 82 .

FIG. 89 is a diagrammatic illustration showing a perspective view of aportion of an AIP in accordance with some embodiments of the apertureshown in FIG. 82 .

FIG. 90 is a diagrammatic illustration showing a perspective view of atapered element in accordance with some embodiments of the apertureshown in FIG. 82 .

FIG. 91 is a diagrammatic illustration showing a side view of thetapered element shown in FIG. 90 .

FIG. 92 is a diagrammatic illustration showing a top view of the taperedelement shown in FIG. 90 .

FIG. 93 is a diagrammatic illustration showing a bottom view of thetapered element shown in FIG. 90 .

FIG. 94 is a diagrammatic illustration showing a perspective view amultipart embodiment of a tapered element in accordance with someembodiments of the aperture shown in FIG. 82 .

FIG. 95 is a diagrammatic illustration showing a side view of themultipart tapered element shown in FIG. 94 .

FIG. 96 is a diagrammatic illustration showing a curvature or taper ofan edge or periphery of a tapered element in accordance with someembodiments of the aperture shown in FIG. 82 .

FIG. 97 is a diagrammatic illustration showing a side view of onealternative embodiment of a tapered element in accordance with someembodiments of the aperture shown in FIG. 82 .

DETAILED DESCRIPTION

With reference to FIGS. 1 and 2 , front and side-sectional views areshown, respectively, of an illustrative radio frequency (RF) aperture,including an interface printed circuit board (i-PCB) 10 having a frontside 12 and a back side 14, and an array of electrically conductivetapered projections 20 having bases 22 disposed on the front side 12 ofthe i-PCB 10 and extending away from the front side 12 of the i-PCB 10.The illustrative i-PCB 10 is indicated in FIG. 1 as having dimensions5-inch by 5-inch—this is merely a non-limiting illustrative example of acompact RF aperture. FIG. 1 shows the front view of the RF aperture,with an inset in the upper left showing a perspective view of oneelectrically conductive tapered projection 20. This illustrativeembodiment of the electrically conductive tapered projection 20 has asquare cross-section with a larger square base 22 and an apex which doesnot extend to a perfect tip but rather terminates at a flattened apex 24(in other words, the electrically conductive tapered projection 20 ofthe inset has a frustoconical shape). This is merely an illustrativeexample, and more generally the electrically conductive taperedprojections 20 can have any type of cross-section (e.g. square as in theinset, or circular, or hexagonal, or octagonal, or so forth). The apex24 can be flat, as in the example of the inset, or can come to a sharppoint, or can be rounded or have some other apex geometry. The rate oftapering as a function of height (i.e. distance “above” the base 22,with the apex 24 being at the maximum “height”) can be constant, as inthe example of the inset, or the rate of tapering can be variable withheight, e.g. the rate of tapering can increase with increasing height soas to form a projection with a rounded peak, or can be decreasing withincreasing height so as to form a projection with a more pointed tip.Similarly, as best seen in FIG. 1 , the illustrative array of theelectrically conductive tapered projections 20 is a rectilinear arraywith regular rows and orthogonal regular columns; however, the array mayhave other symmetry, e.g. a hexagonal symmetry, octagonal symmetry, orso forth. In the illustrative example of the inset, the square base 22and square apex 24 lead to the electrically conductive taperedprojection 20 having four flat slanted sidewalls 26; however, othersidewall shapes are contemplated, e.g. if the base and apex are circular(or the base is circular and the apex comes to a point) then thesidewall will be a slanted or tapering cylinder; for a hexagonal baseand a hexagonal or pointed apex there will be six slanted sidewalls, andso forth.

With continuing reference to FIGS. 1 and 2 and with further reference toFIG. 3 , the RF aperture further comprises RF circuitry, which in theillustrative embodiment includes chip baluns 30 mounted on the back side14 of the i-PCB 10. Each chip balun 30 has a balanced port P_(B) (seeFIGS. 3 and 6 ) electrically connected with two neighboring electricallyconductive tapered projections of the array of electrically conductivetapered projections via electrical feedthroughs 32 passing through thei-PCB 10. Each chip balun 30 further has an unbalanced port P_(U) (seeFIGS. 3 and 6 ) connecting with the remainder of the RF circuitry. Theillustrative RF circuitry further includes RF power splitter/combiners40 for combining the outputs from the unbalanced ports P_(U) of the chipbaluns 30. As seen in FIG. 3 , the illustrative electrical configurationof the RF circuitry employs first level 1×2 RF power splitter/combiners40 ₁ that combine pairs of unbalanced ports P_(U), and second level 1×2RF power splitter/combiners 40 ₂ that combine outputs of pairs of thefirst level RF power splitter/combiners 40 ₁. This is merely anillustrative approach, and other configurations are contemplated, suchas using 1×3 (which combine three lines), 1×4 (combining four lines), orhigher-combining RF power splitter/combiners, or various combinationsthereof. The illustrative RF circuitry further includes a signalconditioning circuit 42 interposed between each unbalanced port P_(U) ofthe chip baluns 30 and the first level 1×2 power splitter 40 ₁. Thesignal conditioning circuit 42 connected with each unbalanced portincludes: an RF transmit amplifier T; an RF receive amplifier R; and RFswitching circuitry including switches RFS configured to switch betweena transmit mode operatively connecting the RF transmit amplifier T withthe unbalanced port and a receive mode operatively connecting the RFreceive amplifier R with the unbalanced port.

With continuing reference to FIGS. 1-3 and with further reference toFIGS. 4 and 5 , a compact design is achieved (e.g., depth of 3-inches inthe non-limiting illustrative example of FIG. 3 ) in part by employingone or more printed circuit boards (PCBs) including at least the i-PCB10. In the illustrative example shown in FIG. 3 , the chip baluns 30 aremounted on the back side 14 of the i-PCB 10. Optionally, the otherelectronic components may also be mounted on the back side of the i-PCB10 on whose front side 12 the array of electrically conductive taperedprojections 20 are disposed. However, there may be insufficient realestate on the i-PCB 10 to mount all the electronics of the RF circuitry.In the illustrative embodiment, this is handled by providing a secondprinted circuit board 50 which is disposed parallel with the i-PCB 10and faces the back side 14 of the i-PCB 10. Said another way, the secondprinted circuit board 50 is disposed on the (back) side 14 of the i-PCB10 opposite from the (front) side 12 of the i-PCB 10 on which theelectrically conductive tapered projections 20 are disposed. The RFcircuitry comprises electronic components mounted on the second printedcircuit board 50, which may also be referred to herein as a signalconditioning PCB or SC-PCB 50, and additionally or alternativelycomprises electronic components mounted on the i-PCB 10 (typically onthe back side 14 of the i-PCB, although it is also contemplated (notshown) to mount components of the RF circuitry on the front side of thei-PCB in field space between the electrically conductive taperedprojections 20. If the SC-PCB 50 is provided, as shown in FIG. 2 it issuitably secured in parallel with the i-PCB 10 by standoffs 54, andsingle-ended feedthroughs 52 are provided to electrically interconnectthe i-PCB 10 and the SC-PCB 50 (see FIG. 3 ). If the RF circuitry isunable to fit onto the real estate of two PCBs 10, 50, a third (andfourth, and more, as needed) PCB may be added (not shown) to accommodatethe components of the RF circuitry.

FIG. 4 shows a front view of the i-PCB 10 including vias and mountingholes and diagrammatically indicated locations of baluns 30 and resistorpads as indicated in the legend shown in FIG. 4 . (The resistors areused to terminate the unused side of the pyramids to help lower radarcross section).

With reference to FIG. 2 and with further reference to FIG. 5 , theillustrative RF aperture has an enclosure 58 which in the illustrativeexample is secured at its periphery with the periphery of the i-PCB 10so as to enclose the RF circuitry. This is merely one illustrativearrangement, and other designs are contemplated, e.g. both PCBs 10, 50may be disposed inside an enclosure (although such an enclosure shouldnot comprise RF shielding extending forward so as to occlude the area ofthe RF aperture). FIG. 5 diagrammatically illustrates a rear view of theenclosure 58 of the RF aperture, showing diagrammatically indicated RFconnectors (or ports) 60 (also shown or indicated in FIGS. 2 and 3 ),control electronics 62 (for example, illustrative phased array beamsteering electronics 63 shown by way of non-limiting illustration; theseelectronics 62, 63 may be mounted on the exterior of the enclosure 58and/or may be disposed inside the enclosure 58 providing beneficial RFshielding), and a power connector 64 for providing power for operatingthe active components of the RF circuitry (e.g. operating power for theactive RF transmit amplifiers T and the active RF receive amplifiers R,and the switches RFS). The particular arrangement of the variouscomponents 60, 62, 63, 64 over the area of the back side of theenclosure can vary widely from that shown in FIG. 5 , and moreover,these components may be located elsewhere, e.g. the RF connectors 60could alternatively be located at an edge of the RF aperture or soforth. It will also be appreciated that the RF aperture could beconstructed integrally with some other component or system—for example,if the RF aperture is used as the RF transmit and/or receive element ofa mobile ground station, a maritime radio, an unmanned aerial vehicle(UAV), or so forth, in which case the enclosure 58 might be replaced byhaving the RF aperture built into a housing of the mobile groundstation, maritime radio, UAV fuselage, or so forth. In such cases, theRF connectors 60 might also be replaced by hard-wired connections to themobile ground station, maritime radio, UAV electronics, or so forth.

With particular reference to FIG. 3 , an illustrative electricalconfiguration for the illustrative RF circuitry is shown. In thisnon-limiting illustrative example, the array of electrically conductivetapered projections 20 is assumed to be a 5×5 array of electricallyconductive tapered projections 20, as shown in FIGS. 1 and 4 . Thebalanced ports P_(B) of the chip baluns 30 connect adjacent (i.e.neighboring) pairs of electrically conductive tapered projections 20 ofthe array so as to receive the differential RF signal between the twoadjacent electrically conductive tapered projections 20 (in receivemode; or, alternatively, to apply a differential RF signal between thetwo adjacent electrically conductive tapered projections 20 in transmitmode). As detailed in Steinbrecher, U.S. Pat. No. 7,420,522 which isincorporated herein by reference in its entirety, the tapering of theelectrically conductive tapered projections 20 presents a separationbetween the two electrically conductive tapered projections 20 thatvaries with the “height”, i.e. with distance “above” the base 22 of theelectrically conductive tapered projections 20. This provides broadbandRF capture since a range of RF wavelengths can be captured correspondingto the range of separations between the adjacent electrically conductivetapered projections 20 introduced by the tapering. The RF aperture isthus a differential segmented aperture (DSA), and has differential RFreceive (or RF transmit) elements corresponding to the adjacent pairs ofelectrically conductive tapered projections 20. These differential RFreceive (or transmit) elements are referred to herein as aperturepixels. For the illustrative rectilinear 5×5 array of adjacentelectrically conductive tapered projections 20, this means there are 4aperture pixels along each row (or column) of 5 electrically conductivetapered projections 20. More generally, for a rectilinear array ofprojections having a row (or column) of N electrically conductivetapered projections 20, there will be a corresponding N-1 pixels alongthe row (or column). FIG. 3 shows a QUAD subassembly, which is aninterconnection of a row (or column) of four pixels. As there are fourrows, and four columns, this leads to 4×4 or 16 such QUAD subassemblies.The resistor pads are used as terminations for the unused edges of theperimeter pyramids to prevent unnecessary reflections. Without theresistors mounted via the resistor pads, those surfaces would be leftfloating and could re-radiate incident RF energy, causing an enhancedradar cross section.

In the illustrative embodiment shown in FIG. 3 , the second level 1×2 RFpower splitter/combiner 40 ₂ of each QUAD subassembly connects with anRF connector 60 at the backside of the enclosure 58. Hence, as seen inFIG. 5 , there are eight RF connectors for the eight QUAD subassemblies,denoted in FIGS. 4 and 5 as the row QUAD subassemblies N1, N2, N3, N4and the column QUAD subassemblies M1, M2, M3, M4. The Gnd(N) row and theGnd(M) column are circuit grounds to allow a common path for currentflow from the captured RF energy along the perimeter sides of thepyramids. The use of the QUAD subassemblies permits a high level offlexibility in RF coupling to the RF aperture. For example, theillustrative phased array beam steering electronics 63 may beimplemented by introducing appropriate phase shifts ϕ_(N), N=1, . . . ,4 for the row QUAD subassemblies N1, N2, N3, N4 and phase shifts ϕ_(M),M=1, . . . , 4 for the column QUAD subassemblies M1, M2, M3, M4 to steerthe transmitted RF signal beam in a desired direction, or to orient theRF aperture to receive an RF signal beam from a desired direction(transmit or receive being controlled by the settings of the switchesRFS of the signal conditioning circuits 42). Other applications that maybe implemented by the RF aperture include: simultaneous“Transmit/Receive, dual circular polarization modes”, and “Scalability”by physically locating multiple DSAs in close physical proximity givingthe combined effect of increased aperture size. In an alternativeembodiment diagrammatically shown in FIG. 3 , the RF connectors 60 maybe replaced by analog-to-digital (A/D) converters 66 and digitalconnectors 68 via which digitized signals are output. More generally,the ND conversion may be inserted anywhere in the RF chain, for exampleA/D converters could be placed at the outputs of the signal conditioningcircuits 42 and the analog first and second level RF powersplitter/combiners 40 ₁, 40 ₂ then replaced by digital signal processing(DSP) circuitry.

The described electronics employing PCBs 10, 50, chip baluns 30, andactive signal conditioning components (e.g. active transmit amplifiers Tand receive amplifiers R) advantageously enables the RF aperture to bemade compact and lightweight. As described next, embodiments of theelectrically conductive tapered projections 20 further facilitateproviding a compact and lightweight broadband RF aperture.

FIG. 6 shows a side sectional view of one illustrative embodiment inwhich each electrically conductive tapered projection 20 is fabricatedas a dielectric tapered projection 70 with an electrically conductivelayer 72 disposed on a surface of the dielectric tapered projection 70.The dielectric tapered projections may, for example, be made of anelectrically insulating plastic or ceramic material, such asacrylonitrile butadiene styrene (ABS), polycarbonate, or so forth, andmay be manufactured by injection molding, three-dimensional (3D)printing, or other suitable techniques. The electrically conductivelayer 72 may be any suitable electrically conductive material such ascopper, a copper alloy, silver, a silver alloy, gold, a gold alloy,aluminum, an aluminum alloy, or so forth, or may include a layered stackof different electrically conductive materials, and may be coated ontothe dielectric tapered projection 70 by vacuum evaporation, RFsputtering, or any other vacuum deposition technique. FIG. 6 shows anexample in which solder points 74 are used to electrically connect theelectrically conductive layer 72 of each dielectric tapered projection20 with its corresponding electrical feedthrough 32 passing through thei-PCB 10. FIG. 6 also shows the illustrative connection of the balancedport P_(B) of one chip balun 30 between two adjacent electricallyconductive tapered projections 20 via solder points 76.

FIGS. 7 and 8 show an exploded side-sectional view and a perspectiveview, respectively, of an embodiment in which the dielectric taperedprojections 70 are integrally included in a dielectric plate 80. Theelectrically conductive layer 72 coats each dielectric taperedprojection 70 but has isolation gaps 82 that provide galvanic isolationbetween the neighboring dielectric tapered projections 20. The isolationgaps 82 can be formed after coating the electrically conductive layer 72by, after the coating, etching the coating away from the plate 80between the electrically conductive tapered projections 20 togalvanically isolate the electrically conductive tapered projectionsfrom one another. Alternatively, the isolation gaps 82 can be definedbefore the coating by, before the coating, depositing a mask material(not shown) on the plate 80 between the electrically conductive taperedprojections 20 so that the coating does not coat the plate in theisolation gaps 82 between the electrically conductive taperedprojections whereby the electrically conductive tapered projections aregalvanically isolated from one another. As seen in the perspective viewof FIG. 8 , the result is that the dielectric plate 80 covers (andtherefore occludes) the surface of the i-PCB 10, with the electricallyconductive tapered projections 20 extending away from the dielectricplate 80.

With particular reference to FIG. 7 , in one approach for the electricalinterconnection, through-holes 82 pass through the illustrative plate 80and the underlying i-PCB 10, and rivets, screws, or other electricallyconductive fasteners 32′ pass through the through-holes 82 (note thatFIG. 7 is an exploded view) and when thusly installed form theelectrical feedthroughs 32′ passing through the i-PCB 10. (Note, theperspective view of FIG. 8 is simplified, and does not depict thefasteners 32′). The use of the dielectric plate 80 with integraldielectric tapered projections 70 and the combined fastener/feedthroughs32′ advantageously allows the electrically conductive taperedprojections 20 to be installed with precise positioning and withoutsoldering.

In the embodiments of FIGS. 6-8 , the electrically conductive coating 72is disposed on the outer surfaces of the dielectric tapered projections70. In this case, the dielectric tapered projections 70 may be eitherhollow or solid.

With reference to FIGS. 9 and 10 , as the dielectric material issubstantially transparent to the RF radiation, the electricallyconductive coating 72 may instead be coated on inner surfaces of the(hollow) dielectric tapered projections 70. FIG. 9 shows a sidesectional view of such an embodiment, while FIG. 10 shows a perspectiveview. The embodiment of FIGS. 9 and 10 again employs a dielectric plate80 including the dielectric tapered projections 70. As seen in FIG. 10 ,by coating the electrically conductive coatings 72 on the inner surfacesof the hollow dielectric tapered projections 70, this results in theelectrically conductive coating 72 being protected from contact from theoutside by the dielectric plate 80 including the integral dielectrictapered projections 70. This can be useful in environments in whichweathering may be a problem.

It is to be appreciated that the various disclosed aspects areillustrative examples, and that the disclosed features may be variouslycombined or omitted in specific embodiments. For example, one of theillustrative examples of the electrically conductive tapered projections20 or a variant thereof may be employed without the QUAD subassemblycircuitry configuration of FIGS. 2-5 . Conversely the QUAD subassemblycircuitry configuration of FIGS. 2-5 or a variant thereof may beemployed without the dielectric/coating configuration for theelectrically conductive tapered projections 20. Likewise, the chipbaluns 30 may or may not be used in a specific embodiment; and/or soforth.

With reference to FIGS. 11 and 12 , further embodiments of the multiplesensor elements/pyramids 20 of the DSA 102 (e.g., scalable, modularboard) are described. The sensor elements/pyramids can be formed on, forexample, the front side 12 of the circuit board 10 as an array andfunction as a radiation interface. The senor elements/pyramids 20 ofFIGS. 11 and 12 each include multiple electrically conductive plates 90(FIG. 12 ) that together form the pyramid and/or the sensorelements/pyramids can each be formed of a single plate 91 (FIG. 11 )that, for example, wraps in a conical fashion. In some embodiments, eachsensor element/pyramid 20 is hollow, that is, includes a void 92. Thevoid 92 may be formed by an inner portion of either the multiple plates90 and/or single conical plate 91. This occurs, for example, when thesensor element/pyramid 20 is supported from an outside portion, creatingthe void 92 in the center. In one embodiment, the multiple plates 90 ofthe sensor element/pyramid can come close to each other, but not touch.In other words, the conductive plates of the sensor element/pyramid canform a gap 94 (FIG. 12 ). Similarly, the single conical plate 91 canhave an upper opening or gap 95. The gap 94, 95 can exist between theplates and/or between the plates and a support of fixture that containsor holds the plates of the sensor elements/pyramids of the DSA. In someembodiments, the sensor elements/pyramids 20 can be formed of a solidmaterial. The surface of the plate(s) 90, 91 that form the sensorelement/pyramid can be used (e.g., the skin depth) for conductivity. Inother words, the surface of the sensor elements/pyramids 20 can be usedto transfer current from, for example, a wavelength or RF signal,causing the resistance of the sensor elements/pyramids to increaseresultant from the current riding the surface of the sensorelements/pyramids (i.e., attenuation). The plate(s) 90, 91 can be formedof any highly electrically conductive material. In some embodiments, theplate(s) 90, 91 of the sensor elements/pyramids may be formed ofsomething other than an electrically conductive material, e.g. theelectrically conductive material can be, for example, printed or wrappedonto dielectric plates as shown in FIGS. 6-10 . For example, conductivematerial can be spray-coated onto the plates that form the sensorelements/pyramids. The thickness of the coating can be varied to achievedesired skin depths. The embodiments of FIGS. 11 and 12 further includea conductor or electronic component 96 on the front side 12 of thecircuit board 10. The embodiment of FIG. 12 further includes a bend 97defined at the intersection of the lower end of the plates 90 and theconductor or electronic component 96.

With continuing reference to FIGS. 11 and 12 , in some embodiments it iscontemplated to leverage the voids 92 defined by the hollow electricallyconductive tapered projections 20 to accommodate one or more electroniccomponents 100 disposed on the front side 12 of the printed circuitboard 10. Electrical vias, i.e. feedthroughs 102 passing through thei-PCB 10 provide electrical communication between the front-sideelectronics 100 and electronics/electrical circuitry disposed on thebackside of the i-PCB 10 and/or the single-ended feedthroughs 52electrically interconnecting the i-PCB 10 and the SC-PCB 50 (see FIG. 3). The embodiment of FIG. 12 further includes an optional recess or hole104 in the front surface 12 of the i-PCB 10 that receives the electroniccomponent(s) 100. Other electronic component mounting arrangements arealso/alternatively contemplated, e.g. sockets for integrated circuits(ICs) or so forth. Advantageously, the hollow electrically conductivetapered projections 20 serve as Faraday cages protecting the interiorelectronic component(s) 100 from RF interference. Placing electronics100 inside the hollow electrically conductive tapered projections 20also provides for a more compact design (for example possibly providingsufficient real estate to eliminate the need for the second PCB 50 shownin FIG. 3 ).

With reference to FIG. 13 , in another illustrative RF apertureembodiment, a radio frequency (RF) transparent material 110 covers thesensor elements/pyramids (that is, the electrically conductive taperedprojections 20 of other embodiments described herein). The RFtransparent material 110 serves as a support/fixture forcontaining/holding plates 112 of the elements/pyramids of the DSAcaptured in the cover. Plates 112 can be captured in the cover 110 usingor with the assistance of an adhesive 114. In some embodiments, acircuit board can be configured to be attached to the plate(s) (e.g. thei-PCB 10). The circuit board can receive the foot or base of the plateand the plate can be optionally electrically attached (e.g., soldered)to the circuit board. In an alternative embodiment, the conductiveplates 112 can be formed of printed circuit boards. As noted above,together the printed circuit boards, forming the conductive plates, cancreate or include a void (e.g. voids 92 of the embodiments of FIGS. 11and 12 ). In some embodiments, electronic components 110 (see FIGS. 11and 12 ) of the DSA or sensor elements/pyramids can be housed within thevoid and combined, for example, in a differential mode. Alternatively,the electronic components could be directly attached to the DSA boardvia screws 116 or holes 118, sensor elements/pyramids, to each other orto something else. In some embodiments, the RF transparent materialcover 110 includes an optional filler 120 that is filled with a variabledielectric.

With reference to FIGS. 14-17 , the DSA (e.g., scalable, modular board)can include multiple sensor elements/pyramids 20 formed of conductiveplates. FIG. 14 shows a top view of an example in which the electricallyconductive tapered projections 20 are of equal size and distributed overthe i-PCB 10 as a rectilinear array. FIGS. 15 and 16 show top and sideviews, respectively, of an example in which electrically conductivetapered projections 20 of equal size are distributed over the i-PCB 10as a rectilinear array, and smaller-sized electrically conductivetapered projections 20 s are interspersed in the space between therectilinear array. FIG. 17 shows an example in which the electricallyconductive tapered projections 20 are of equal size but are distributedover the i-PCB 10 as other than a rectilinear array, e.g. with unequalspacings between neighboring electrically conductive tapered projections20. The sensor elements/pyramids 20, 20 s can be formed on, for example,the i-PCB 10 as an array and function as a radiation interface. In someembodiments, the signal capture area of the sensor elements/pyramids 20can be uniformly distributed over the area of the array or radiationinterface. This may be accomplished, for example, by locating a centerpoint of the sensor elements/pyramids 20 at equal distance relative toeach other (FIG. 14 ). In an alternative embodiment, shown in FIGS. 15and 16 , the center points of a first set of sensor elements/pyramids 20with a first height H1 (FIG. 16 ) can be located at an equal distancerelative to each other to uniformly distribute the signal capture areaover the area of the array or radiation interface and second sets ofsensor elements/pyramids 20 s with a second (or more different) heightsH2, H3 that vary can be located at random or to achieve desiredpropagation or signal capture in the signal capture area defined by thefirst set of sensor elements/pyramids 20. In other words, the secondsets of sensor elements/pyramids 20 s do not have to be evenly spacedfrom each other. In yet another embodiment, shown in FIG. 17 , the(first) set of sensor elements/pyramids 20 with a first height H1 can belocated at random distances relative to each other to achieve a desiredpropagation or signal capture. The (first) set of sensorelements/pyramids 20 with a first height H1 can also be located toachieve a desired signal capture area. In an alternative embodiment (notshown), the first set of sensor elements/pyramids can include a firstheight H1 that varies to achieve a desired propagation or signal capturein the signal capture area. The first set of sensor elements/pyramids,organized at random or to achieve a desired propagation or signalcapture in the signal capture area, can also be interspersed with thesecond sets of sensor elements/pyramids as shown in FIGS. 15 and 16 .

With reference to FIGS. 18-20 , in some embodiments the DSA (e.g.,scalable, modular board) can include multiple sensor elements/pyramids20 formed of conductive plates (or otherwise formed, e.g. using metalliccoatings on dielectric projections as described in other embodimentsherein). In some embodiments, the multiple sensor elements/pyramids 20are each formed of a single plate wrapped to create a conical-shapedsensor element/pyramid, multiple conductive plates configured to form avoid (FIGS. 18 and 20 ), or can be formed as a solid (FIG. 19 ). Asnoted above, in alternative embodiments, electronic components of theDSA or sensor elements/pyramids can be housed within the void of FIGS.18 and 20 and combined, for example, in a differential mode.Alternatively, the electronic components could be directly attached tothe DSA board, sensor elements/pyramids, to each other or to somethingelse. In some embodiments, shown in FIGS. 18-20 , dielectric materialcan surround or be otherwise configured to form to the sensorelements/pyramids 20 of the DSA. In other words, the dielectric materialcan fill in gaps created between the sensor elements/pyramids. Thedielectric material can form distinct layers, as in the embodiments ofFIGS. 18-20 . The layers can be formed of different materials each withdifferent permittivity values. Alternatively, the layers can be formedof a same material and the permittivity of the single material can bechanged. For example, as shown in FIG. 20 , air holes or otherdielectric voids may be formed in the dielectric material (e.g., the airspaces can be fractionalized). The density of the air holes or otherdielectric voids determines the overall dielectric constant. In oneembodiment, shown in FIG. 20 , lots of air holes or other dielectricvoids are formed in the upper most layer of the dielectric material,which results in more of a match of free space to dielectric material inthe upper most layer. The second most layer has reduced air holes orother dielectric voids, decreasing the ratio of air holes or dielectricvoids to dielectric material. For each layer of dielectric material, theratio of air holes or dielectric voids to dielectric material isdecreased (i.e., dielectric lensing). The dielectric material and ratioof air holes or dielectric voids to dielectric material can be chosenbased on a desired propagation of RF signals through the dielectricmaterial inlaid between the sensor elements/pyramids of the DSA. As thesignal or wavelength hits the dielectric material, the propagationchanges. In other words, the wavelength of the incoming signal isshortened. For example, when measuring the voltage differential, thereis an increased voltage differential if/when the wavelength shortens.

With reference to FIGS. 21-23 , in some embodiments, dielectric materialcan surround or be otherwise configured to form to the sensorelements/pyramids 20 of the DSA. In other words, the dielectric materialcan fill in gaps created between the sensor elements/pyramids. In theillustrative embodiments of FIGS. 21-23 , the dielectric material isformed of single or multiple material that, together, form a gradedindex (e.g., no discontinuities). In other words, there is a gradedindex of dielectric material. As shown in FIG. 23 , air holes or otherdielectric voids can be formed in the graded index of dielectricmaterial. The density of air holes or other dielectric voids to thegraded index of dielectric material can change based on, for example, adesired signal propagation through the graded index of dielectricmaterial.

With reference to FIG. 24 , an enlarged view of the graded dielectric ofthe embodiment of FIG. 23 is shown with additional descriptive notation.As shown in FIG. 24 , the volumetric fraction of air holes or otherdielectric voids to the dielectric material results in an overalldielectric constant. By changing the permeability of the graded index ofdielectric material or changing the dielectric constant of the gradedindex of dielectric material filled in between the gaps of the sensorelements/pyramids 20 of the DSA, as the signal or wavelength hits thegraded index of dielectric material the propagation changes. Forexample, as shown in FIG. 24 , the signals may propagate in a firstdielectric. At an upper most portion of the graded index of dielectricmaterial, the dielectric material and the volumetric fraction of airholes or other dielectric voids have a same dielectric constant (e.g.,based on the volumetric fraction of the material that has the openings).As the number or volume of air holes or other dielectric voids todielectric material decreases, the dielectric constant decreases. Eachdielectric has a real part and a complex part. In the complex part, aloss tangent, which also is a dissipation factor, exists. This causesattenuation. The goal is to limit attenuation by minimizing the complexpart on the dielectric material. This is how the dielectric materials orcomposite materials are selected.

In some embodiments, the sensor elements/pyramids of the DSA can beformed of the dielectric materials and include conductive platesconfigured to support the dielectric material. Holes or other dielectricvoids can be formed in the dielectric material supported by theconductive plates. The holes or other dielectric voids can be used tovary the effective dielectric constant. Resistivity determines the loss.

Although FIGS. 18-24 show the dielectric material ending before the peakof the sensor elements/pyramids 20 of the DSA, the dielectric materialcould go beyond the peaks of the sensor elements/pyramids of the DSAand/or completely encapsulate the sensor elements/pyramids of the DSA.

In some embodiments, the RF aperture (e.g. DSA) is a modular plate.Multiple DSAs can be selectively put together to form larger DSAs.

In further variants, the DSAs could be acoustic based DSAs or magneticbased DSAs. Magnetic based DSAs would allow efficient magnetic fieldcapture as low as tens of Hertz frequencies. This would potentiallyminimize propagation. Acoustic would allow the DSA to be deployed onsubmarines and to operate under the water.

With reference to FIG. 25 , the DSA (e.g., scalable, modular board) caninclude multiple sensor elements/pyramids 20 formed of conductive plates(or otherwise formed as described in various embodiments herein). In oneembodiment, a base 10 of the DSA can be formed of a printed circuitboard (e.g., the described i-PCB) configured to support the sensorelements/pyramids 20. The circuit board can include multiple openingswhere the baluns (i.e., the sensor elements/pyramids 20) are loaded. Thecircuit board, with openings, creates a form factor that can be slidablyreceived on, for example, a 3-D printed form factor (e.g., blocks,etc.). In other words, the circuit board together with the baluns canform a “smart board” configured to store the intelligence (e.g., using aprocessing node 900, see FIG. 28 ) of the DSA. The smart board can be,for example, injection molded. This smart board can be slidably receivedon any form factor. The smart board can be efficiently manufactured.

As shown in FIG. 26 , the DSA (e.g., scalable, modular board) caninclude multiple sensor elements/pyramids 20 formed of conductive plates(or otherwise formed as described in various embodiments herein). Whilethe previous embodiments have employed a flat i-PCB 10, in theembodiment of FIG. 26 the shaping of the DSA is domed (or, moregenerally, has a non-flat or curved surface 130, e.g. with a fixedcurved radius in some more specific embodiments). The domed-shaped DSAof FIG. 26 (including sensor elements/pyramids 20 formed along thecurved surface 130) can support beam-forming and beam-steering. Forexample, the DSA can be configured to attach to a curved surface suchas, for example, the exterior of an airplane. Using beam-forming, acertain series of amplitudes may be applied to the sensorelements/pyramids 20 of the DSA to knock out side loads and create aconcentrated, directed beam steered directionally to the DSA. In otherwords, the amplitudes of different elements can be changed and the phaseshifts between adjacent elements used to direct concentrated beams atthe sensor elements/pyramids 20 of the DSA. The illustrative DSA of FIG.26 also includes optional dielectric material 132 disposed between thesensor elements/pyramids 20, for example as described with reference toFIGS. 18-24 .

With reference to FIG. 27 , a network 200 is shown, including accessnode 208 (e.g., signal source/node for detecting signals, etc.) directlycommunicating with one DSA 206, and relay node 204 (e.g., could be, forexample, an interferer node, used to relay signal information, etc.)communicating with another DSA 202 (e.g., scalable, modular board thatincludes, for example, multiple elements, which can be formed as anarray and function as an electromagnetic radiation interface or otherconductive material).

FIG. 28 shows a diagrammatic representation of a processing node 900including a communication interface 902, a user interface 904, and aprocessing system 906 with storage 908 storing software 910. Theprocessing node 900 may, for example, be used in conjunction with theDSA of FIG. 25 .

Some further contemplated optional aspects and/or extensions are listedas follows. Antenna that includes a single port. Cable transmission lineor transmission line that is not formed as an integral part of thesensor element. Inner conductor and/or dielectric material formed withthe electrically conductive tapered projection and/or sensor without aplate (e.g., the sensor is formed as part of the bristle structure).Electrically conductive tapered projections formed of something otherthan metal or that is formed of multiple antennas. Transmission linethat corresponds to multiple electrically conductive tapered projectionsor antennas. Random signal capture area. Shorter length of electricallyconductive tapered projections compared to wavelength. Do not terminatefollicle in a resistive element that matches the impedance of thefollicle (e.g., find another way to ‘electrically black’ the signal).Don't digitally convert the signals to create a digital replica of theincident electromagnetic energy. Don't use electronic modules to createan active surface that controls the amplitude of the reflected signals(e.g., amplify the signal by a factor relating to real magnitude). Pixelpartition elements (electrically conductive tapered projections) that donot correspond to a single horizontal/vertical circuit board. Usesomething other than RF waves (e.g., acoustic or magnetic aperturedesigned equivalently to the RF aperture embodiments described herein).Provide the partition elements to each have a frequency dependenteffective area. Form the circuit boards as part of the partitionelements. In other words, form partition elements of some material thatholds or supports a circuit board. The partition elements are alsocontemplated to be the circuit board. Printed partition element thatincludes a printed circuit board formed as part of it. Use a printedcircuit board on the partition element or formed with the partitionelement to guide RF signals and or disperse, etc., on the rest of thepartition element. In some contemplated embodiments, the circuit boardsterminate in a balanced transmission line. The support substrate (e.g.illustrative i-PCB 10) could alternatively be formed as a portion of theelectrically conductive tapered projections or partition elements.Conductive “seats” or “pads” that are not positioned on the substrate orthat surround the electrically conductive tapered projections orpartition elements. This refers to “conductive” seats or pads such ascopper. Seats or pads that are not conductive could use a material thataffects the acoustic response, such as a polymer (in the case of anacoustic aperture). Similarly, different properties could be provided totransform the RF waves.

In the following, some further illustrative implementations of theelectrically conductive tapered projections are described. In someembodiments, these are solid elements, as in the following examples.

The protrusions should be firmly mounted to a surface (flat, or curved)and make discrete, electrical contact along each face of the protrusion.The protrusions may be non-round protrusions, having at least 3 facesand 3 edges connecting the faces. Undue ‘play’ or uncoupled movementbetween the interface board and the protrusion can result in decreasedRF performance.

With reference to FIGS. 29-31 , an embodiment employs electricallyconductive tapered protrusions 300 and an interface board 302 whichcontains conductive traces 304. The protrusion 300 is made from a solidconductive material, such as metal bar stock, e.g. of copper or aluminumwhich are readily available, high performance, and cost effective. Theillustrative electrically conductive tapered protrusion 300 has theshape of a four-sided pyramid. The protrusion 300 is held against theboard 302 with a screw or other threaded fastener 306 causing consistentpressure to be made along the base edges. This pressure ensures anelectrical contact because the conductive traces 304 are slightly higherthan the non-conductive elements of the circuit board 302, and theconductive traces 304 are exposed, as seen in FIG. 29 . The top view ofthe configuration with the protrusion 300 mounted is shown in FIG. 30 ,while FIG. 31 shows a top view of the interface board 302 in isolation.In this design, the protrusion 300 has at least one small nub (and inthe illustrative embodiment two small nubs 308) that maintain the properorientation of the protrusion 300 with respect to the conductivesurfaces. The protrusion 300 has a centered hole 310 that is threaded toreceive the screw 306 after the screw passes through a through-hole 312in the interface board 302. The mounting method is independent of thelength of protrusion 300, and so the height of the protrusion 300 abovethe surface of the board 302 is a free design parameter.

With reference to FIGS. 32-35 an embodiment is shown which permits theprotrusion mounting to work with a non-PCB interface board (that is, aninterface board that does not include printed circuitry). The mountingmethod uses sheet goods to electrically connect the pyramids withperpendicular boards (not shown in FIGS. 32-36 ) below the interfaceboard. FIGS. 32 and 33 show side and bottom isolation views,respectively, of a suitable electrically conductive tapered protrusion300, which may be of the same design as in FIGS. 29-31 , e.g. having theshape of a four-sided pyramid. Here the protrusion 300 sits on anelectrically conductive (e.g., metal) mount 320. The mount 320 is shownin isolation in FIG. 34 , with the nubs 308 captured in the holes 322 ofthe mount 320. Tabs 324 of the mount (labeled in FIG. 34 ) then insertand protrude through an interface board 330, as shown in the explodedperspective view of FIG. 35 . Screws 306 then go from the backside ofthe interface board 330, through the respective mounts 320, and into thecentered holes 310 of the respective protrusions 300. Again, the mountscan be used with protrusions 300 of different heights. In thisconfiguration the mount 320 can be designed so that the size of the baseis interchangeable as well. So long as the tabs 324 that mount throughthe interface board 330 are in the same location, the size of the mountcan be changed at will. As shown in FIG. 35 , this design allows for theinterface board 330 to be an electrically non-conductive housing, whichmay contain electrical circuitry for operating the array of electricallyconductive tapered protrusions 300 in RF transmit and/or RF receivemode(s).

With reference to FIG. 36 , another embodiment employs an electricallyconductive tapered protrusion 340 in which the nubs 308 of theembodiments of FIGS. 29-35 are replaced by recesses 348. In thisembodiment, the interface board 330 of the embodiments of FIGS. 29-35 isreplaced by an interface board 350 which includes nubs 352 that matewith the recesses 348. In other words, the positive nubs 308 arereplaced with holes 348, which in some manufacturing processes reducesmachining time, and thus cost, and results in less material waste. To doso, the interface board 350 is designed to supply the nubs 352 itself.The interface board 350 may for example be injection molded or producedby additive manufacturing, in both cases the inclusion of the nubs 352is of little consequence to material or tooling costs. For the samestrength as the metal nub 308 on the solid metal protrusion 300, the nub352 on the non-metal interface board 350 should be larger due to itsmaterial composition, but this is to no detriment because the increasedhole size in the mount 320 and in the protrusion 340 do not affect costor performance.

In a variant approach, the use of nubs is eliminated by using a secondscrew, with both screws being offset from the center of the protrusionbeing secured. Using two screws requires two tapping steps, and doublesthe number of screws, and doubles the time spent fastening.

With reference to FIGS. 37-39 , in some designs the electricallyconductive tapered protrusions are faceted with various geometries. Asmentioned, the electrically conductive tapered protrusions 300 as shownin FIGS. 30 and 35 are four-sided pyramids with four-fold rotationalsymmetry. FIG. 37 shows an embodiment which is also a four-sidedpyramid, but with only two-fold rotational symmetry. This design couldsupport different sensitivities and signal chain complexities alongopposing orthogonal polarizations. FIG. 38 shows an embodiment in whichthe electrically conductive tapered protrusions are six-sided (i.e.hexagonal) pyramids with six-fold rotational symmetry. A hexagonalstructure provides three different polarizations. This is useful when itis necessary to finely measure or transmit polarization, or when thenumber of signal chains per surface area is higher, thus increasingtransmit power and reducing noise for that same area. FIG. 39 shows anembodiment in which the electrically conductive tapered protrusions arethree-sided (i.e. triangular) pyramids with three-fold rotationalsymmetry. These have similar properties to the hexagonal design of FIG.38 . More generally, any configuration where the geometry can tesselateis possible, with the most straightforward being a geometry that cantessellate with only itself.

In the following, some further illustrative implementations of theelectrically conductive tapered projections are described. In theseembodiments, the projections are hollow elements, e.g. formed by platesas in the following examples.

Manufacturing of solid electrically conductive tapered protrusions usessubstantial amounts of interior material that does not affect the RFperformance, as the electromotive force only flows on the outsidesurface of the protrusion, to a depth equaling the skin depth of theparticular frequency of the coupled RF radiation. Employing hollowelectrically conductive tapered protrusions can reduce weight, materialcost, and fabrication cost. Hollow protrusions can be made from sheetgoods, such as electrically conductive plates. In the variousembodiments next discussed, the electrically conductive plates may havea positive support, or may be freestanding or self-supporting plates, ormay have a negative support.

Key attributes for DSA market acceptance include Size, Weight, Power,and Cost (SWAP-C) per equivalent performance. Using faceted electricallyconductive tapered projections (such as those of FIGS. 30, 35, and 37-39; as opposed to conical projections) facilitates machining the facetedprojections from solid aluminum or copper stock. While convenient,significant material is used in solid projections, with significant tooltime, raising both the cost and weight of the DSA. Being that theelectromagnetic wave only travels a small depth (i.e. the skin depth)into the protrusion, only the first few micrometers of the outer surfaceneed to be electrically conductive. The calculation for skin depth is asfollows:

$\begin{matrix}{\delta = \sqrt{\frac{\rho}{\pi f_{0}\mu_{r}\mu_{0}}}} & (1)\end{matrix}$

Where δ is the skin depth, ρ is the resistivity of the material, f₀ isthe frequency-of-interest, μ_(r) is the relative permeability of thematerial (˜1 for copper and aluminum), and μ₀ is the permeability offree space. For the frequencies-of-interest to the current generation ofDSA design, i.e., 100 MHz and greater, the skin depth is less than 10micrometers. The result is that the conductive surface of the DSAprotrusions only need to be a few skin depths, e.g. 5-10 microns, inthickness on each side to support the current flow from the protrusionto the signal chain.

With reference to FIGS. 40 and 41 , an electrically conductive taperedprojection 400 is suitably milled from bar stock, and then is processedby a finishing step where excess material is removed. FIG. 40 shows anexample of this approach where a single tapped screw hole 402 ismaintained in the center of the structure and the remaining material ismilled out, retaining a thickness of material that is appropriate formechanical rigidity. FIG. 40 shows a central cylinder support 404disposed inside the hollow projection 400. The illustrative centralcylinder 404 has a circular cross-section extending to the top of theprotrusion, however this cylinder support could have a square orrectangular cross-section which would be faster to machine with only amoderate penalty in weight. While this solution reduces the weight ofthe projection, it increases the tooling time and thus the cost ascompared with a solid projection, and maintains the same material costas a solid projection.

Rather than subtractive milling, the electrically conductive taperedprojection 400 could be manufactured by casting or additivemanufacturing. Casting reduces manufacturing costs and material waste,but is only suitable in high volume applications. The projection 400manufactured by casting would likely have a rough surface and be thickerthan necessary for mechanical rigidity. For additive manufacturing, thematerial must be conductive limiting the applicable technologies.Generally, additive manufacturing would be most costly then milling, andresult in a rough surface.

In the following, a plate-based approach is described for manufacturingthe electrically conductive tapered projections. Three variants of theplate-based approach are described: an approach using a positivesupport; an approach that is free standing, i.e. self-supporting; and anapproach utilizing a negative support.

With reference to FIGS. 42-48 , an embodiment employing positive supportis described. Here, individual electrically conductive (e.g., metal)tapered plates 420 (shown in isolation in FIG. 42 in alternativeperspective views) are supported internally by a dielectric structure422 shown in FIGS. 43 and 44 in alternative perspective views. Eachelectrically conductive tapered plate 420 has a tab 424 at the bottomthat electrically extends the plate beyond the base of the protrusion tomake electrical connection with an interface board (PCB or not PCB) or aperpendicular boards located below the interface board, or some otherelectronics. Each plate 420 further has a bend 426 in the plate at thepoint where the protrusion ends. The bend 426 permits the plate 420 totravel through the interface board at a ninety-degree angle. Whileoptional, this bent configuration saves material and provides an easierconnection. A third feature is an angled extension 428 below the planeof the tapered projection. This angled extension 428 mates with theinterface board, ensuring a slide into the board and positive capture.It also increases the strength at the bend 426.

The electrically conductive tapered plates 420 are supported by thedielectric structure 422 shown in FIGS. 43 and 44 . This structure hasfour (for the illustrative four-sided faceted projection) tapered (e.g.“V”-shaped) receptacles 430 (labeled in FIG. 43 ) into which fourrespective electrically conductive tapered plates 420 mate. The matingis by the “V”-shaped (or more generally, tapered) receptacles 430capturing the edges of the electrically conductive “V”-shaped (moregenerally, tapered) plates 420, allowing the electrically conductivetapered plates 420 to slide in as shown in alternative perspective viewsof FIGS. 45 and 46 . The electrically conductive tapered plates 420 thusdefine the facets of the electrically conductive tapered projection 400.As seen in FIGS. 44 and 46 , the bottom of the dielectric structure 422has two nubs 432 to prevent rotation once mounted to an interface board440 (shown in isolation in FIG. 47 ) with matched locating holes 442.Additionally, there is a hole 444 in the center that can be threaded toreceive a screw, or smooth for a rivet. The fastener used at this holegoes from the back of the interface board, into the supportingstructure, rigidly holding the entire assembly together. Once assembled,the system has the appearance of FIG. 48 which shows five electricallyconductive tapered projections 420, 422 mounted on the topside, and FIG.49 which shows the backside with the tabs 424 protruding.

Benefits of this plate-based approach include that it is interchangeablewith the a solid projection design, permitting the choice of solid orplate-based projection type to be made for each application.Additionally, the plate design configuration is lighter and hassignificantly less material cost than the solid projection or hollowedprojection approaches. The dielectric support 422 can be formed by aninjection molding process for high manufacturing volume, or via additivemanufacturing at low manufacturing volume. The assembly time isincreased slightly due to the step of inserting the plates into thesupporting structures. One RF performance benefit is that the plates,being electrically isolated, can provide higher cross polarizationisolation as compared with a solid or hollowed out projection in whichthere are conductive paths between the facets.

In the preceding example the internal structure (i.e., dielectricsupport 422) was required to support the plates 420. However, thecomplete isolation of individual sides of the faceted electricallyconductive tapered projections has been shown in experimentation to leadto mechanical resonances that can decrease RF performance. To addressthese issues, in the following some illustrative configurations aredisclosed to provide a freestanding projections that needs no internalstructure. These electrically conductive tapered projections arefabricated using sheet goods, further reducing costs. Any of theexamples could be attached at the edges over the entire length or atpoints through applying solder or creating a tabbed connection where atab located on one face slides into a cut on the adjacent space. Thepoint-based soldering solutions could be ideal in that it eliminatesmechanical resonances by rigidly attaching the faces, while stillpermitting a great deal of cross polarization isolation.

Some illustrative examples that follow show the projection coming to apoint for simplicity. However, coming to a point is not necessary, andfor mechanical strength or ease of fabrication the top of the protrusioncan be a shaped matched to the bottom of the protrusion, but smaller insize.

An example is shown in FIGS. 50 and 51 . In this example, FIG. 51 showsa faceted electrically conductive tapered projection 450 that is formedby folding a single-piece cut-out 452 from a metal sheet as shown inFIG. 50 . As best seen prior to folding in FIG. 50 , the cut-out 452includes the four facets 454 (in this example) which meet at a smallsquare apex facet 456 (or, alternatively, at an apex point as seen inalternative embodiments of FIGS. 52-54 ). The facets 454 of thesingle-piece cut-out 452 are folded at their junctions with the apexfacet 456 (or apex point) to form the faceted electrically conductivetapered projection 450. Each facet 454 includes a tab 458 distal fromits junction with the apex facet 456 (or apex point) that mates into aninterface board 460 as seen in FIG. 51 , to electrically connect withthe RF circuitry. In the assembled projection 450 of FIG. 51 , edges ofthe neighboring facets 454 may optionally be connected by soldering orby mating tabs (features not shown in FIGS. 50 and 51 ). As just noted,the apex facet 456 is optional but can add mechanical strength (if theapex facet 456 is omitted then the four facets come together at an apexpoint).

With reference to FIG. 52 , a variant embodiment is shown, with thefaceted electrically conductive tapered projection 470 shown in thebottom part of FIG. 52 and the corresponding single-piece cut-out 472shown in the top part of FIG. 52 . This embodiment omits the apex facet456 of the embodiment of FIGS. 50 and 51 , so that the four facets 474of this embodiment come to a point. Additionally, the tabs 458 of theembodiment of FIGS. 50 and 51 are omitted, and in their place a bottomplate 476 is attached to one of the facets 474 in the cut-out. Thebottom plate 476 has an opening 477 for capturing a fastener 478, suchas a bolt head or a rivet. If a bolt is used, attachment is performedbefore completion of the folding because once the folding is completedthe inside of the projection 470 is not accessible. Once folded theprojection 470 can be soldered at points or along the entire edge, or atabbed connection could be used (features not shown). Alternatively, thebottom edges of the facets 474 could be soldered to an interface board,or the bottoms could fold to create a tab that rests on top of theinterface board. This variant is lightweight. It can provide goodcross-polarization isolation. However, the nature of the folding couldresult in variabilities in RF performance since there is no mechanicalconnection. Additionally, as shown in FIG. 52 with a single screw, thepyramid could rotate if only a pressure fit is used to electricallyattach the faces. Having two screws fasten the bottom plate 476 woulddouble the number of attachment steps but eliminate the rotation issue.In this embodiment a PCB is suitably used for the interface board toprovide for electrical connection to the projection 470. Furthermore,variations are contemplated such as providing a bottom plate on morethan one of the facets 474, so when folded the bottom is replicated,thus adding rigidity and consistency at a penalty of material weight andcost.

With reference to FIG. 53 , another illustrative faceted electricallyconductive tapered projection 480 is shown in the bottom part of FIG. 53and the corresponding single-piece cut-out 482 shown in the top part ofFIG. 53 . This embodiment is similar to that of FIGS. 50 and 51 andincludes the four facets 454 with the tabs 458; but the apex facet 456is omitted, so that the four (side) facets come to a point. It shouldalso be noted that further variants are contemplated, such as replacingthe apex facet 456 of the embodiment of FIGS. 50 and 51 with a roundedapex, for example formed by a drawing operation. Regarding the tabs 458of the embodiments of FIGS. 50 and 51 and 53 , the tabs 458 are bent tomeet the interface board 460 at a 90-degree angle when the projection480 is bent into its final shape (e.g., as in FIG. 51 and the bottom ofFIG. 53 ). The tabs 458 can be soldered to electrical traces of theinterface board 460 when the interface board 460 is a printed circuitboard (PCB). This permits a strong mechanical and electrical connectionof the electrically conductive tapered projection 450, 480 to theinterface board 460. Alternatively, the tabs 458 can pass through theinterface board and attach to the perpendicular board below. Optionally,neighboring edges of the facets 454 can be joined using solder or a taband receiver arrangement (not shown). This method improves on the flatbottom version in that it has reduced weight and requires no mechanicalconnection other than the joining of the tab to a PCB. The use of thetabs 458 reduces assembly time and overall system Size, Weight, Power,and Cost (SWAP-C) compared to the approach of using the bottom plate 476as in the embodiment of FIG. 52 .

With reference to FIG. 54 , another illustrative faceted electricallyconductive tapered projection 490 is shown in the bottom part of FIG. 53and the corresponding single-piece cut-out 492 shown in the top part ofFIG. 53 . This embodiment employs four facets 494 each with a tab 498offset-positioned at a corner of the facet 494. Here the interface board460 has a thickness at least the depth of the triangular facet 494 addedto the tab. While the illustrative tab 498 is offset to one side, itcould alternatively be in the middle with a triangle added to eitherside.

With reference to FIG. 55 , an embodiment employing plates with negative(i.e. external) support is disclosed. A DSA may include a radome (i.e.,a structural enclosure that may optionally be weatherproof) to protectthe electrically conductive tapered projections and provide a safesurface for external contact. In this embodiment, a radome 500 includesor defines a form 502 with tapered projection-shaped recesses 504. Toconstruct electrically conductive tapered projections 506, a sheet ofmetal is laid on top of the form 502 (e.g. at a positiondiagrammatically indicated in FIG. 55 by dashed line 508), then a punchis applied to push the sheet metal into the tapered projection-shapedrecesses 504. Alternatively, a separate sheet may be punched to formeach projection 506. The punch may be shaped in the same cross sectionas the projections 506. (Note, in diagrammatic FIG. 55 , a gap is shownbetween the surfaces of the tapered projection-shaped recesses 504 andthe projections 506 in order to distinguish them; however, in actualfabrication the tapered projections 506 will be pressed against andcontacting the corresponding surfaces of the tapered projection-shapedrecesses 504). This approach has certain benefits. It facilitatesautomation of DSA assembly. It also provides support for the projections506 thereby permitting thinner material and a higher level ofenvironmental robustness. The radome 500 should be made of a dielectricmaterial, such as plastic, and can be fabricated by a manufacturingapproach such as injection molding or three-dimensional (3D) printingtechnology. Injection molding can build strong, light and low-costradomes. Note the form 502 need not be solid and could alternatively bemostly vacant.

In the following, some further illustrative implementations aredescribed, which address an issue recognized herein that the interfaceboard, if metallic (for example, a PCB with a ground plane) canadversely impact RF performance of the DSA.

The DSA architecture works best with no electrically conductive materialimmediately behind the gap between electrically conductive taperedprojections. On the other hand, most radio frequency componentryperforms best when mounted proximate to a ground plane, for example on aPCB with a ground plane. To address this issue, some embodimentsdisclosed herein employ PCBs that are mounted perpendicular to thesurface on which the projections are mounted.

In a DSA design such as that of FIG. 2 , the projections 20 are mounteddirectly to the printed circuit board (PCB) 10, and the opposing side ofthe PCB 10 is used to mount RF componentry (e.g., the chip baluns 30 inthe example of FIG. 2 ). The PCB 10 has at least 2 layers, withconductive traces connecting the protrusions 20 on the ‘top’ to thebaluns 30, and either the inner layer (when more than 2 layers arepresent) or an outer layer as a flooded ground plane. A flooded groundplane provides a low resistance surface for electricity to flow byfilling the surface, to the extent possible, with a conductive material.The ground plane is included to improve RF componentry performance.

With reference to FIG. 56 , this is diagrammatically illustrated byshowing the electrically conductive tapered projections 20 and theunderlying ground plane 510 (which is part of the PCB 10 of theembodiment of FIG. 2 ). The ground plane 510, being integral to the samesubstrate (i.e. PCB 10) to which the projections 20 are mounted, resultsin an electrically conductive surface being mounted less than onecomplete wavelength away from the gaps between the protrusions 20 at thebases of the protrusions 20. FIG. 56 diagrammatically shows theresulting RF interference due to the reflection of the incoming radiofrequency wave back into the projection space. While the interferencecan be both constructive or destructive, the overall result is adecrease in wideband performance and an increase in design complexityrequired to resolve such interference at multiple arrival angles andfrequencies.

One solution (not illustrated) is to replace the continuous ground planewith a ground plane extending under the bases of the projections, butnot extending between the projections. In such an approach, the RFcomponentry would be sufficiently miniaturized so that it fits entirelyunder the bases of the projections. However, this approach would requirea complex “grid-like” ground plane and highly miniaturized RFcomponents.

With reference to FIG. 57 , another solution is illustrated. By movingthe conductive surface, i.e., the ground plane 510, further then onewavelength away from the bases of the projections 20, the PCB can beused in an orientation perpendicular to the impingent electromagneticwave (e.g., as in FIG. 2 ). This approach involves providing a standoff520 from the protrusion 20 to the PCB that provides rigid support, and aconductive connection 522 for each face of the projection 20, e.g. fourconnections 522 when the projection 20 is square or rectangular. In avariant embodiment (not shown), the conductive connections 522 providethe rigid support, so that the separate standoff 522 could optionally beeliminated. The standoffs provide a separation 524 between the bases ofthe projections 20 and the ground plane 510. This approach is mostsuitable for higher RF operating frequencies, as for low frequencies therequisite separation 524 becomes large, and this can reduce rigidity andlead to failure under shock and vibration. For example, at 400 MHz, theseparation 524 provided by the standoffs would need to be approximately0.75 meters. By contrast, at 10 GHz the separation 524 provided by thestandoffs would only need to be 3 centimeters.

With reference to FIG. 58 , another solution is to mount theelectrically conductive tapered projections 20 on an electricallynon-conductive interface board 550, and to mount the RF componentry 552on perpendicular printed circuit boards (PCBs) 560 that are orientedperpendicularly to the interface board 550. That is, rather thanmounting the projections 20 on an interface board that is a PCB with anelectrically conductive ground plane, in the embodiment of FIG. 58 adielectric substrate interface board 550 is used. A top surface of thedielectric interface board 550 supports the projections 20, and a set ofPCBs 560 for supporting the RF componentry 552 are orientedperpendicular to the surface 550. The perpendicular PCBs 560 contain orsupport the RF components 552 mounted over ground planes of the PCBs560. In one embodiment (shown in FIG. 58 ) there is a perpendicular PCB560 located between each row of projections 20. In another embodiment(not shown) there is one perpendicular PCB underlying each row ofprojections. Placing the perpendicular PCBs 560 between the rows ofprojections 20 is well-suited for operating the DSA in a differentialmode.

The interface board 550 can be manufactured of any rigid, or semi-rigiddielectric material, such as plastic (e.g., Acrylonitrile butadienestyrene, i.e. ABS). Alternatively, the interface board 550 can be aprinted circuit board (PCB), but one that does not include a continuousground plane. Using a PCB without a ground plane, but with electricallyconductive traces, as the interface board 550 permits easier connectionof signals between the projections 20 to the connections with theperpendicular PCBs 560 (which do have ground planes). In one approach,the connections to the perpendicular PCBs 560 employs card edgeconnectors. Using a PCB without a ground plane as the interface board550 also permits the edges to be terminated with a load directly on thePCB, simplifying design. However, utilizing a PCB without a ground planeas the interface board 550 raises the cost over using a sheet ofdielectric material. The sheet dielectric can be made to capture theperpendicular PCBs via various fastening configurations, such as screwholes with a corresponding right angle bracket, edge connectors, tenons,or so forth. Another option is to create a mount for the projections 20which attaches the projection 20, mount and surface through a screw,rivet, or the like, and the mount mechanically and electrically attachesto the perpendicular PCBs 560. The mount may be soldered or compressiontype, optionally aided by a screw.

In some embodiments, the interface board 550 forms part of a housing forthe DSA, for example the interface board 550 can be one side of afive-sided box enclosure housing. The front surface mounts theprotrusions and an optional radome, while the bottom has connectionpoints for an optional backside cover. (See FIGS. 64 and 65 ).

In some embodiments, edges of the perpendicular PCBs 560 are secured tothe interface board 550. In this arrangement, the perpendicular boards560 are subject to stress when under shock or vibration. These stressescan be relieved by the rigid mounting to the interface board 550, and/orby inclusion of a second support board 562 oriented parallel with theinterface board 550 to secure the edges of the perpendicular boards 560distal from the interface board 550, as shown in FIG. 59 . The secondsupport board 562 should also not contain a ground plane, unless theperpendicular boards 560 are of sufficient size to position the secondsupport board 562 more than one RF wavelength away from the bases of theprojections 20.

FIG. 60 shows a plan-view of a DSA incorporating the concepts describedin FIG. 58 . Here the upper surface of the interface board 550 is a PCB(without a ground plane) enabling interconnections 564 of theperpendicular row boards 560 to columns of projections 20, and optionaledge terminations 566. The design of FIG. 60 can also optionally includethe second support board 562 (occluded from view in FIG. 60 ), which canimprove mechanical rigidity of the assembly so as to improve robustnessagainst shock and vibration. If the second support board 562 isincluded, then it can optionally include additional routing ofelectrical connections between the perpendicular row boards 560,simplifying the connection to further signal chain elements. Aspreviously noted, if the perpendicular boards 560 are of sufficient sizeto position the second support board 562 more than one RF wavelengthaway from the bases of the projections 20, then the second support board562 may also include a ground plane and RF componentry.

With reference to FIGS. 61-63 , in another embodiment two orthogonalsets of perpendicular boards 560, 570 are provided. The set ofperpendicular boards 560 (also referred to as “row boards”) areperpendicular to the interface board 550, while another set ofperpendicular boards 570 (also referred to as “column boards”) areperpendicular to the interface board 550 and are also perpendicular tothe row boards 560. In this embodiment, the row boards 560 and columnboards 570 include cutouts 572 to enable the row and column boards 560,570 to mate together to form a two-dimensional grid of perpendicularboards 560, 570 all of which are perpendicular to the interface board550. This facilitates providing electrical connections to both rows andcolumns of projections 20, and the grid of intermeshed row and columnboards 560, 570 provides additional rigidity to the assembly. Thecutouts 572 allow the crossing row and column PCBs 560, 570 to cross andintermesh. If the cutouts 572 are mechanically affixed when assembled(e.g. by glue), or have an interference fit, then the assembly becomes aself-supporting two-dimensional grid. Although not shown in FIGS. 61-63, the second support board 562 of the embodiment of FIG. 59 can also beincluded to further enhance rigidity. The benefits of this method ofusing crossing row and column perpendicular boards 560, 570 include thatit simplifies electrical connection to both rows and columns ofprojections 20, improves rigidity of the assembly, and optionally allowsfor omitting the second support board 562 (due to the improved rigidityprovided by the intermeshing row and column boards 560, 570). Again, theinterface board 550 can be made of any electrically non-conductingmaterial, or can be a PCB without a flood fill (that is, without acontinuous ground plane). However, the use of both column and row boards560, 570 can alleviate the need for electrical conductors on theinterface board 550, thus enabling the interface board 550 to be asimple dielectric board with no printed circuitry.

With reference to FIGS. 64 and 65 , a complete DSA assembly includingthe embodiment of FIGS. 61-63 is shown. FIG. 64 shows an explodedperspective view of the DSA assembly. This embodiment does not includethe second support board 562. In the DSA assembly of FIG. 64 , theinterface board 550 is a front surface of a five-sided housing orenclosure 580, which is shown in isolation in FIG. 65 . The protrusions20 are disposed on respective mounts 320 (he mounts 320 were previouslyillustrated in, and described with reference to, FIG. 34 ) secured byscrews 306 (as previously illustrated in, and described with referenceto, FIG. 36 ). The DSA assembly of FIG. 64 further includes a radome 582with associated gasket 584. The radome 582 fits over the electricallyconductive tapered projections 20 and over a portion or all of theenclosure or housing 580, and is secured by fasteners 586. On thebackside of the enclosure or housing 580, a rear cover or support 588and associated gasket 590 is provided, and secured to the DSA assemblyby fasteners 592. This design utilizes the interface board 550 as adielectric surface that also forms the front face of the five-sizedhousing 580 (see also FIG. 65 ). The housing 580 contains grooves on theinternal faces (not shown) that capture the edges of the perpendicularboards 560, 570, thereby increasing shock and vibration survivability.The interface board 550 (and optionally the entire housing 580) may be asingle-piece plastic component, for example fabricated by additivemanufacturing or injection molding. As noted, the projections 20 connectto respective mounts 320 which then mechanically and electrically attachto the row and column boards 560, 570. The mounts 320 can be made fromstamped metal, which significantly decreases the material andfabrication cost of the projections 20.

The DSA designs disclosed herein can be employed with a wide range of RFcomponentry configurations. In the following, some illustrative signalchains suitably used with the disclosed DSAs are presented.

The DSA interfaces with free space for electromagnetic capture and/orlaunch (depending on application) in a differential mode, which meansthat it works off a difference in RF signal between two points. Mostcommercial off-the-shelf RF circuitry assumes a single ended mode ofoperation where a signal is on a single conductor and is referenced to aground. The DSA architecture can be made to work with the single endedcircuitry through a transformer referred to as a balun (i.e.,“balanced-unbalanced). This is illustrated in FIG. 66 showing a sideview (upper drawing) and top view (lower drawing). FIG. 66 shows an RFcoupling in which baluns 600 connect the electrically conductive taperedprojections 20 and convert the differential signal to a single endedsignal. FIG. 66 shows a 3×2 DSA configuration (which can be extended toany M×N DSA configuration, where M and N are each integers greater thanor equal to one). In this case the electrically conductive taperedprojections 20 are four-sided faceted pyramids, and each facet isconnected to the opposing facet of a neighboring projection 20 throughthe differential side of the balun 600. Herein, this space is referredto as a pixel.

Generally, the baluns are connected to some form of signal chain, twoparticular embodiments are shown in FIG. 67 . The embodiments of FIG. 67are for a transceiver, i.e. a DSA that provides both transmit (TX) andreceive (RX) operations. If only a transmitter, i.e. a DSA that onlyprovides transmit (TX) operation; or only a receiver, i.e. a DSA thatprovides only receive (RX) operation, is desired, then the switch 614(upper time-division duplexing signal chain 610) or circulator orduplexer 616 (lower frequency division duplexing or full duplexingsignal chain 612) can be omitted, and the unneeded pathway (TX or RX)can be omitted. FIG. 67 also shows the direct attachment of the signalchain 610, 612 to the balun 600, equating a one to one ratio between thenumber of opposing faces of the projections 20 and signal chains.

The upper part of FIG. 67 shows an example of a signal chain 610 usingan RX/TX switch 614. The design of the signal chain 610 does notdirectly power the receive circuit with the transmit circuit. The switch614 serves the function of isolating the TX and RX pathways. The circuit610 cannot both transmit and receive at the same time, often called TimeDomain Duplexing (TDD). However, a DSA electrical architecture may havesome signal chains 610 operating in RX mode and some signal chainsoperating in TX mode, simultaneously, to provide both transmit andreceive operation at the same time, albeit with a decrease in apertureefficiency. Use of the switch 614 in the signal chain 610 has thebenefit that switches are low cost, readily available, can handle highpower, and can operate over a wide bandwidth.

The lower part of FIG. 67 shows an example of a signal chain 612 that iscapable of operating in either Frequency Division Duplexing (FDD) orFull Duplex (FD). FDD allows simultaneous transmit and receive bytransmitting and receiving on separate frequencies and filtering out thetransmit frequency from the received signal. Here the switch 614 isreplaced by a component 616 such as a diplexer or circulator. A diplexerdivides transmit and receive by frequency, whereas a circulator ackslike a series of gates permitting the transmit energy to largely avoidreflecting into the RX pathway. The diplexer is not adjustable andrequires a designed-in approach to frequency operation (e.g., designatedtransmit and receive frequencies or frequency bands). Typicalcommercially available circulators do not exceed approximately 1 GHz (orone octave) in bandwidth. This places constraints on a DSA in using asignal chain such as the illustrative signal chain 612. FD means thesignal chain can operate in both transmit and receive modes on the samefrequency at the same time, while maintaining isolation of the RX pathfrom the TX path. This is commonly achieved through using differentantennas or a circulator, combined with a cancellation circuitry thatconnects the TX path to the RX path through an inverse signal. The DSAarchitecture can achieve full duplex operation by having the TX and RXpathways on different sets of projections 20, and thus using differentsignal chains for each mode, or by including a circulator.

In either TDD, FDD, or FD mode, the signal chain can be varied tosupport a multitude of different electrical architectures, each withtheir own SWAP-C/performance tradeoffs.

With reference to FIG. 68 , an illustrative 4×4 DSA supports up to 40individual signal chains, where the signal chains are diagrammaticallyindicated by circles 620 in FIG. 68 . There are benefits to thisapproach, such as the ability to use low power TX amplifiers (oftencalled power amplifiers, PAs), a lower noise floor due to averaginguncorrelated noise of the RX amplifiers (often called low noiseamplifiers, LNAs), increased signal dynamic range, aperture subset-ingwhere a portion of the aperture is dedicated to a function and adifferent portion dedicated to a different function, and dynamic andarbitrary beam forming and polarization generation. However, thisperformance comes at a penalty in SWAP-C because each signal chainconsumes space and power and raises the cost.

With reference to FIG. 69 , it is thus sometimes desirable to combinethe signals so that one signal chain supports multiple pixels. One wayis to combine the pixels into rows and columns, which maintains multiplepolarization operation and beam steering and forming in azimuth andelevation. To combine pixels, a combiner or splitter (e.g., combiner 632or combiners 634 in the illustrative signal chain 630 of FIG. 69 ) isinserted into the signal chain at one or more locations in the TX/RXpathways. The combiner 632, 634 is a bidirectional device, meaningcurrent can flow either way, or both ways simultaneously. FIG. 69 showsthat a combiner 632 can be placed in between the duplexer and the balun,or alternatively combiners 634 can be placed upstream of a poweramplifier (PA) 636 in the TX path and downstream of a low noiseamplifier (LNA) 638 in the RX path. (While FIG. 69 shows the combiner632 coupled with a single illustrative pixel via the illustrated balun600, more generally the combiner 632 can be coupled with multiple pixelsvia the respective baluns of the pixels. Likewise, while theillustrative combiners 634 are coupled with a single illustrative pixelvia the power amplifier 636 and low noise amplifier 638 of theillustrative pixel, more generally the combiners 634 can be coupled withmultiple pixels via the respective components 634, 636 of the pixels.)The first location (i.e. combiner 632) is lower cost, because onecombiner 632 is used for both TX and RX pathways; however, thisarrangement suffers a performance penalty because the combiner 632typically has limited power handling capability and inserts a signalreduction (a loss) in the RX pathway. The second location (i.e.combiners 634) doubles the number of combiners required but permits theuse of per pixel PAs 636, increasing the overall efficiency ofconversion of electrical power to RF power, and allows the LNA 638 toovercome the loss of the combiner 634 on the RX pathway and reduce theoverall noise figure of the system since the per pixel thermal noise isuncorrelated and reduces system noise at a ratio proportional to1/√{square root over (Number Pixels)}. Conversely embodiments employingthe combiner 632 use a single LNA 638 for many pixels and receives lessnoise figure benefit.

The signal chain 630 of FIG. 69 assumes that there are sufficient numberof signal chains present to perform beam steering and beam forming, ifdesired. While some beam forming and steering can be done with twosignal chains, four signal chains provides a better performing solution.The highest cost and highest power consuming portion of the signal chainis often the analog to digital conversion, and the digital signalprocessing required to performing the operations needed for beamsteering and forming.

With reference to FIG. 70 , a signal chain 640 illustrates one way toreduce system cost. The signal chain 640 includes a phase shifter ortime delay 642 downstream of the digital to analog converter (DAC) 644,and a phase shifter or time delay 646 upstream to the analog to digitalconverter (ADC) 648. This method reduces the number of required signalchains, and in some cases only one signal chain is needed. The tradeoffis that the time shifters or delays 642, 646 can limit wide bandoperations in some implementations.

In all signal chains shown herein, it is noted that the digital toanalog converter optionally can be followed by a mixer that raises thefrequency of the signal, and the analog to digital converter optionallycan be preceded by a mixer that lowers the frequency of the signal.

With reference to FIG. 71 , some RF components can operate on signalsdifferentially instead of single ended. Using such “differential” RFcomponents enables the DSA to operate with a fully differential signalchain 650 as shown in FIG. 71 . Here the inputs are maintained as abalanced pair all the way to the conversion from or to a digital word atthe ADC 648 or DAC 644. The power amplifier (PA) 636 and the low-noiseamplifier (LNA) 638 process differential signals in this embodiment. Theillustrative embodiment of FIG. 71 further includes a switch (oralternatively a duplexer or circulator) 652 to provide time-division orfrequency-division duplexing of the TX and RX differential paths, and anoptional filter 654 upstream of the LNA 638. It is noted that theswitch, duplexer, or circulator is coupled to one or more aperturepixels without an intervening balun.

A variant embodiment may employ a semi-differential signal chain (notshown) where differential signals are maintained to a location short ofthe DAC and ADC, and baluns are used to convert at that point.

The combiners each insert a loss, are limited in channel count, andincrease SWAP-C. Various designs can be employed to mitigate theseeffects.

With reference to FIG. 72 , an example is shown in which the combiner632 is included after the signal chain 660 (e.g., this could be thesignal chain 630 of FIG. 69 , or the signal chain 640 of FIG. 70 ) andfans out to 4 pixels. These pixels are shown in a row, and the combiner632 is a 4-1 combiner utilized in front of the signal chain 660. In thisexample, all 4 pixels receive the same signal, and pixel level steeringalong the azimuth is not possible. An optional modification is to placea phase shifter between the combiner and baluns. The approach representsa low power, low cost configuration. Note that these examples couldeasily be extending to larger DSAs, e.g., a 10×10 DSA requiring 9-1combiners.

FIG. 73 shows an example of how the combiner 632 can be constructedusing multiple combiners 634 in series to create a combiner with largerfanout, or enable phase shifting across multiple pixels. FIG. 73 showstwo 2-1 combiners 634 stacked in series. One may choose to do thisbecause of SWAP-C or performance characteristics of the 2-1 vs 4-1combiner, or the unavailability of the needed combiner fanout. Anotherreason may be because it is easier to equal total trace lengths from onepixel to another so as not to induce unequal time delays on signallines. Additionally, one could place a mixer in between the combiners634 permitting some beam forming and steering between the groups.

FIG. 74 shows that the combiner approach need not be homogenous, i.e.,the use of combiners is not balanced between the pixels. In the exampleof FIG. 74 , a 3-1 combiner 672 connects a first signal chain 670 withthree pixels, while a fourth pixel has a straight connection to a secondsignal chain 680. This approach could be useful when the DSA is designedto process multiple signals of interest simultaneously, with differentpower/sensitivity needs. In this case when the full DSA performance isneeded then the two signal chains 670, 680 are combined in the digitaldomain.

FIG. 75 shows yet another nonlimiting illustrative example, whichincreases the performance by segregating the TX and RX pathways from theaperture via duplexers 690 (which may be switches, circulators,diplexers, et cetera). As shown in FIG. 75 , a TX signal chain 700 feedsinto a first 4-1 combiner 702 to drive power amplifiers (Pas) 704 totransmit via pixels of the DSA. An RX signal chain 710 receives signalvia a second 4-1 combiner 712 after amplification by low noiseamplifiers (LNAs) 714 (which may optionally contain a pre-filter). Here,a doubling in the number of combiners is necessary, but the performanceis thereby increased. The LNAs 714 can negate the loss of the combiners,and one is no longer restricted to the power limitations of thecombiners because the Pas 704 are downstream.

FIGS. 76-81 present some further examples with variousperformance/SWAP-C trade space positions. Note that in these examples,combiners 632 of FIG. 69 are used, which interface directly with thebalun 600. It is noted that all of these examples could alternatively beimplemented with the combiners 634 in the 2^(nd) position of FIG. 69 .

FIG. 76 shows a 5×5 pixel DSA embodiment that offers four signal chainsin horizontal polarization and four signal chains in verticalpolarization, using combiners 632 which are all 5-1 combiners. Thisconfiguration pairs well with Software Defined Radios (SDRs), which havepower of two (i.e., 2^(n)) channel counts, e.g. SDRs with 2³=8 channelsare commercially available. This design allows simultaneous operation onboth polarizations, the ability to measure incoming polarization, andthe ability to beam steer and form in both azimuth and elevation. Adrawback of this design in the context of the illustrative 5×5 pixel DSAis that it employs 5-1 combiners, which is not a common fanout.

With reference to FIG. 77 , to mitigate the need for uncommon 5-1combiners in the context of the illustrative 5×5 pixel DSA, the designof FIG. 77 can be employed, in which the pixels on one vertical and onehorizontal perimeter are not brought into the signal chain, causing aslight reduction in effective aperture area. Thus, only one face of theprojections 20 are in use. Here the combiners 632 are all 4-1 combiners.This approach permits the more common 4×1 combiner fanouts to be used,as powers of 2 are most popular. To make better use of the unused faces,the approach of FIG. 74 could be applied to permit an additional signalof interest to be investigated.

When a single polarization is of interest, or beam steering and formingare only necessary in one polarization, the approach of FIG. 78 isuseful. Here the rows are connected by combiners 632 served by foursignal chains 630 as already described with reference to FIG. 76 .However, in the embodiment of FIG. 78 the columns are combined into asingle signal chain 720 by a 4-1 combiner 722 fanning out to four 5-1combiners 724. This configuration is useful, for example, if two signalsof interest are in operation and forming and steering are not needed onone of those signals.

FIG. 79 is a DSA architecture that serves a single signal chain 730 withno capability to measure or control polarization, or beam form/steer.The single signal chain is coupled with the rows and columns by a 2-1combiner 731 fanning out to two 4-1 combiners 732 each in turn fanningout to four 5-1 combiners 734. This architecture is, for example, usefulto support an existing single channel radio that needs efficient,ultrawideband performance.

FIG. 80 shows a DSA in which each pixel has its horizontal and verticalpolarizations combined, and is connected to its own signal chain. Thisapproach is useful with low noise and high power efficiency arerequired, and robust beamforming is needed, but the beam pattern andreception pattern are to be symmetrical in polarization.

With reference to FIG. 81 , one benefit of a DSA is its ultrawidebandwidth and ability to support many signals simultaneously. However, agiven DSA implementation may be limited by bandwidth of the dataconverters. To mitigate this limitation, the architecture of FIG. 81 canbe used in any of the preceding examples. As shown FIG. 81 , after thepixels are combined into rows, columns or some other configuration, theyare then split out to multiple converters. For the transmit (TX) path,multiple DAC converters 750 are coupled via combiners 752 to a poweramplifier (PA) 754. For the receive (RX) path, multiple ADC converters760 are coupled via combiners 762 to a low noise amplifier (LNA) 764,optionally with pre-filter 766. Note that the converter is considered toinclude the appropriate filtering and mixers. This architecture issuitable, for example, when the LNA and PAs are present, to reduce theimpact of losses in the combiners.

In accordance with some suitable embodiments disclosed herein, FIGS. 82through 85 show an RF aperture 1000 provisioned with a plurality ofelectrically conductive tapered elements 2000, wherein adjacent pairs ofthe tapered elements 2000 define aperture pixels of a DSA. Specifically,FIG. 82 is a diagrammatic illustration showing a perspective view of theaperture 1000 with selected elements (e.g., such as a housing or radome1002 of the aperture 1000) depicted in phantom to show underlying and/orinterior elements and/or components of the aperture 1000; FIG. 83 is across-section view of the aperture 1000 taken along the section line A-Ashown in FIG. 82 ; FIG. 84 is a diagrammatic illustration showing apartial perspective view of selected interior elements and/or componentsof the aperture 1000, e.g., with the housing or radome 1002 removed; andFIG. 85 is a diagrammatic illustration showing a partially exploded viewof the aperture 1000 as depicted in FIG. 84 .

In some suitable embodiments, the housing or radome 1002 is constructedof a material and/or otherwise made to be transparent and/or largelytransparent to RF signals and/or radiation. For example, in someembodiments, the housing or radome 1002 may be constructed frompolytetrafluoroethylene (PTFE) or another like polymer material. In somesuitable alternative embodiments, the housing or radome 1002 may beconstructed from acrylonitrile butadiene styrene (ABS), thermoplasticelastomers (TPE), polycarbonate (PC), polybutylene terephthalate (PBT),polypropylene (PP), nylon (e.g., such as nylon 12), or combinationsthereof or other suitable materials. Optionally, the housing or radome1002 does not include any metallic parts or coatings, e.g., which mightpotentially interfere with the transmission of RF signals and/orradiation therethrough. In practice, the housing or radome 1002 may beinjection molded or otherwise formed and may have a wall thickness in arange of between about 3 millimeters (mm) to about 4 mm, inclusive. Insome suitable embodiments, the housing or radome 1002 is dimensioned tocontain interior components and/or elements of the aperture 1000 underthe housing or radome 1002 such that a minimum spacing between an innersurface of the housing or radome 1002 and a tip or apex of any of thetapered elements 2000 is maintained greater than or equal to about 6 mm.

As seen in FIG. 82 , the housing or radome 1002 and base plate 1004 incooperation with one another suitably house and/or enclose interiorcomponents and/or elements of the aperture 1000 therein. As shown inFIGS. 82 and 83 , one or more vents 1006-1 and 1006-2 may be arranged onthe housing or radome 1002. In some suitable embodiments, at least oneof the vents 1006-1 may operate as an air intake vent, i.e., such thatoutside air may be drawn therethrough into an interior cavity of theaperture 1000 defined by the housing or radome 1002 and base plate 1004;and at least one of the vents 1006-2 may operate as an exhaust vent,i.e., such that air may be exhausted therethrough from the interiorcavity of the aperture 1000 defined by the housing or radome 1002 andbase plate 1004. In this way, cooling of various elements and/orcomponents housed within the housing or radome 1002 and base plate 1004of the aperture 1000 may be facilitated by an air flow in through theair intake vent 1006-1 and out through the exhaust vent 1006-2.

As seen in FIG. 83 , in some embodiments, a suitable air filter 1008-1may be arranged and/or positioned over, in and/or proximate the airintake vent 1006-1 to trap and/or remove dust, dirt and/or otherunwanted airborne contaminates from the exterior air being drawn intothe interior of the aperture 1000 through the respective air intake vent1006-1. In this way, the air filter 1008-1 may inhibit the potentialcontamination of interior components and/or elements of the aperture1000 with dust, dirt and/or other airborne contaminates that may disruptoperation and/or cause unwanted failure of those interior componentsand/or elements of the aperture 1000. Optionally, a suitable air filter1008-2 may likewise be employed in connection with and/or arrangedproximate to the exhaust vent 1006-2.

In practice, assembly of the aperture 1000 may include sequentiallysecuring various interior element and/or components of the aperture 1000to the base plate 1004, followed by suitably securing the housing orradome 1002 to the base plate 1004 over the various interior elementsand/or components of the aperture 1000. In some suitable embodiments,the housing 1002 may be secured to base plate 1004 with one or morescrews, bolts, nuts and/or other like fasteners, combinations of variousfasteners and/or other suitable fastening mechanisms. In some suitableembodiments, the housing or radome 1002 may be secured to the base plate1004 by threading one or more suitable screws or bolts or the like froman underside of the base plate 1004 and therethrough into mated screw orbolt receiving holes or the like formed in the housing or radome 1002(e.g., where the underside of the base plate 1004 is that side of thebase plate 1004 which is opposite the side of the base plate 1004facing, adjacent and/or proximate to the housing or radome 1002). Insome suitable embodiments, a watertight or other suitably sufficientseal between the housing or radome 1002 and base plate 1004 may beachieved with the use of an o-ring or suitable gasket or the likepositioned and/or squeezed between the housing or radome 1002 and thebase plate 1004.

In some suitable embodiments, as shown in FIG. 84 , the aperture 1000generally includes a transmit (TX) assembly or module 1100 and a receive(RX) assembly or module 1200. In some embodiments, the TX module 1100and RX module 1200 may be largely separate and/or distinct from oneanother (i.e., including separate and/or distinct components and/orelements provided therefor), while still sharing some common componentsand/or elements of the aperture 1000. In practice, the TX module 1100 isprovisioned and/or employed to selectively transmit an over-the-air(OTA) RF signal from the aperture 1000, while the RX module 1200 isprovisioned and/or employed to selectively receive an OTA RF signal bythe aperture 1000. As shown in the illustrated embodiment, the aperture1000 includes the following interior components and/or elements, whichmay be shared by the TX and RX modules 1100 and 1200: a digitalpersonality board (DPB) 1010; one or more standoffs 1012 which distancethe DPB 1010 from the base plate 1004; and a cooling assembly 1300,which may include one or more first heat sink plates 1302, a second heatsink plate 1304 and an array of one or more fans 1306.

In some suitable embodiments, the TX module 1100 may further include: aTX air interface plane (AIP) 1102 which carries a first matrix oftapered element 2000; a TX AIP shield 1104; a TX conditioning board1106; a power supply board 1108; a splitting board 1110; and a splittingboard shield 1112. Likewise, the RX module 1200 may further include anRX AIP 1202 which carries a second matrix of tapered elements 2000; anRX AIP shield 1204; an RX conditioning board 1206; an optional powersupply board 1208; a combining board 1210; and a combining board shield1212.

As shown, the TX AIP shield 1104 may be sandwiched and/or otherwisepositioned between the TX AIP 1102 and the TX conditioning board 1106; afirst one of the first heat sink plates 1302 may be sandwiched and/orotherwise positioned between the TX conditioning board 1106 and thepower supply board 1108; a first end of the second heat sink plate 1304may be sandwiched and/or otherwise positioned between the power supplyboard 1108 and the splitting board 1110; and the splitting board shield1112 may be sandwiched and/or otherwise positioned between the splittingboard 1110 and a first end of the DPB 1010.

As shown, the RX AIP shield 1204 may be sandwiched and/or otherwisepositioned between the RX AIP 1202 and the RX conditioning board 1206; asecond one of the first heat sink plates 1302 may be sandwiched and/orotherwise positioned between the RX conditioning board 1206 and thepower supply board 1208; a second end of the second heat sink plate 1304may be sandwiched and/or otherwise positioned between the power supplyboard 1208 and the splitting board 1210; and the splitting board shield1212 may be sandwiched and/or otherwise positioned between the splittingboard 1210 and a second end of the DPB 1010.

In some suitable embodiments, the power supply board 1108 may be acircuit board including a collection of one or more appropriateelectronic components and/or elements that cooperate to produceelectrical power suitable for supply to and/or operation of variousother boards in the aperture 1000. In practice, the power supply board1108 may be electronically connected to the TX conditioning board 1106and the TX splitting board 1110 to selectively supply electrical powerthereto for operating the same. Likewise, in some suitably embodiments,the power supply board 1208 may be a circuit board including acollection of one or more appropriate electronic components and/orelements that cooperate to produce electrical power suitable for supplyto and/or operation of various other boards in the aperture 1000. Inpractice, the power supply board 1208 is electronically connected to theRX conditioning board 1206 and the RX combining board 1210 toselectively supply electrical power thereto for operating the same. TheDPB 1010 may be electronically connected to either or both power supplyboards 1108 and/or 1208 to selectively receive electrical powertherefrom for operation of the DPB 1010. In some suitable embodiments,either or both power supply boards 1108 and/or 1208 may be additionallyelectronically connected to the fans 1306 to selectively supplyelectrical operating power thereto.

In some suitable embodiments, the power supply board 1208 may merely bea blank or place holder board or an otherwise inactive and/or passiveboard, e.g., without suitable electronic components and/or elements forproducing electrical power, and/or the power supply board 1208 mayoptionally be omitted altogether. In case of the foregoing, the powersupply board 1108 may be suitable provisioned and/or electronicallyconnected to the RX conditioning board 1206 and the RX combining board1210 to selectively supply electrical power thereto for operating thesame, and the DPB 1010 and the fans 1306 may be electronically connectedto the power supply board 1108 to selectively receive electrical powertherefrom for the operation thereof.

In practice, either or both of the respective power supply boards 1108and/or 1208 may be provisioned and/or operate to receive a singleelectrical power input at a given input voltage (e.g., at or about amagnitude of 48 volts (V) or the like), which input is conditioned bythe respective power supply board and/or converted into one or moredesired output voltages (e.g., 12V, 9V, 6V and 5V) as appropriate foruse by one or more different components and/or elements within the RFaperture 1000. The respective power supply boards 1108 and/or 1208 mayfurther be provisioned and/or operate to protected one or more differentcomponents and/or elements within the RF aperture 1000 from transientvoltages and/or power surges. In some suitable embodiments, either orboth of the respective power supply boards 1108 and/or 1208 may bemodular in nature, for example, so that different input voltages can besupported while retaining the same output voltages and form factor. Forexample, without limitations, if a 120 V alternating current (AC) systemwere being manufactured instead of a −48 V direct current (DC) system orif a −48 VDC system were being converted to a 120 VAC system or viceversa, suitable power supply boards 1108 and/or 1208 for the respectivesystems could be interchangeably swapped out, for example, withoutmaking other significant changes to the system to accommodate such powersupply boards provisioned and/or designed to receive differing inputvoltages.

In suitable embodiments, the DPB 1010 may be a digital circuit boardincluding a RF system on chip (SoC) or the like and/or other appropriateelectronic elements and/or components. Suitably, the DPB 1010 may beelectronically connected to the splitting board 1110 and operates toprocess outgoing RF signals and/or control the TX module 1100 fortransmission of the same. In practice, the RF SoC and/or DPB 1010 mayselectively perform digital beam forming processing and include adigital to analog converter (DAC) for converting a digitalrepresentation of an RF signal to an analog signal (e.g., such as amodulated transmit signal) which is in turn supplied to the splittingboard 1110 which is electronically connected to the DPB 1010.

In some suitable embodiments, the splitting board 1110 may be an analogcircuit board including a collection of one or more electroniccomponents and/or elements that cooperate to suitably split and/ordivide the signal received from the DPB 1010. In practice, the splittingboard 1110 splits and/or divides the signal received from the DPB 1010into suitable components, e.g., for respective pixels of the TX AIP1102. In suitable embodiments, the splitting board is furtherelectrically connected to the TX conditioning board 1106. In somesuitable embodiments, the splitting board 1110 splits and/or divides thesignal received from the DPB 1010 into suitable components and maps anumber (N) of channels from the DPB 1010 to a number (M) ofcorresponding tapered elements, e.g., such as the tapered elements 2000of the TX AIP 1102. Suitably, the splitting board 1110 may beprovisioned such that the mapping can be configured and/or readilychanged for different applications and/or system arrangements. In onesuitable embodiment, without limitation, the splitting board 1110 mayoperate to map 8 channels from the DPB 1010 to 8 columns of the taperedelements 2000 in the TX AIP 1102. In another suitable embodiment,without limitation, the splitting board 1110 may operate to map 8channels from the DPB 1010 to 4 columns and 2 rows of the taperedelements 2000 in the TX AIP 1102, for example, without other furthersignificant changes to the system. In still another suitable embodiment,without limitation, the splitting board 1110 may operate to map 16channels from the DPB 1010 to 4 columns and 4 rows of the taperedelements 2000 in the TX AIP 1102.

Suitably, the TX conditioning board 1106 receives the component signalsfrom the splitting board 1110 and prepares them for relaying to therespective pixels of the TX AIP 1102. In practice, the TX conditioningboard may be an analog circuit board including a collection of one ormore electronic components and/or elements that cooperate to suitablycondition the received component signals and relay the same to the TXAIP 1102. For example, the TX condition board 1106 may include one ormore amplifiers that suitably amplify one or more of the componentsignals received from the splitting board 1110. The TX conditioningboard 1106 may further include one or more low pass, bandpass or highpass filters for suitably filtering noise and/or other selected orunwanted components out of various signals. As described later herein,the TX condition board 1106 may also include one or more baluns thatelectrically interconnect respective tapered elements 2000 of the TX AIP1102. In turn, in accordance with the conditioned signal componentsreceived thereby, the TX AIP 1102 produces, transmits and/or otherwiseoutputs an OTA RF signal via the tapered elements 2000 mounted and/orarranged thereon, which collectively function as a DSA. Generally, insome suitable embodiments, operation of the TX module 1100 includes theDPB 1010 providing a modulated TX signal to the splitting board 1110that in turn splits it into individual signals for each of the pixels(e.g., 64) in the TX AIP 1102 for transmission.

As shown, the RX AIP 1202 is provisioned with a matrix of taperedelement 2000 that cooperate to function as a DSA for selectivelyreceiving OTA RF signals. Suitably, the RX AIP 1202 is electronicallyconnected to the RX conditioning board 1206 such that signals fromrespective pixels of the RX AIP 1202 are relayed to the RX conditioningboard. In practice, the RX conditioning board 1206 may be an analogcircuit board including a collection of one or more electroniccomponents and/or elements that cooperate to suitably condition thereceived signals and relay the same to the combining board 1210. Forexample, the RX condition board 1206 may include one or more amplifiersthat suitably amplify one or more of the signals received from the RXAIP 1202. The RX conditioning board 1206 may further include one or morelow pass, bandpass or high pass filters for suitably filtering noiseand/or other selected or unwanted components out of various signals.Suitably, as described later herein, the RX condition board 1206 mayinclude one or more baluns that electrically interconnect respectivetapered elements 2000 of the RX AIP 1202 to define the respective pixelsof the RX AIP 1202.

In practice, the RX conditioning board 1206 may be furtherelectronically interconnected with the combining board 1210 to relay thereceived and conditioned signals thereto. In some suitable embodiments,the combining board 1210 may be an analog circuit board including acollection of one or more electronic components and/or elements thatcooperate to suitably combine selected ones the received signals and inturn relay one or more of the combined signals to the DPB 1010 which iselectronically connected to the combining board 1210. Suitably, the DPB1010 may be provisioned with an analog to digital converter (ADC) thatconverts the received combined signals from an analog format to adigital signal and/or representation thereof and further processes thedigital signal and/or representation accordingly. In some suitableembodiments, the RX module 1200 operates to amplify a received RX signal(e.g., from 64 pixels in the RX AIP 1202) which may be grouped into asingle stronger signal and passed onto the DPB 1010, e.g., forprocessing and beam-steering. In some suitable embodiments, thecombining board 1210 combines signals received from a number (X) of therespective tapered elements, e.g., such as the tapered elements 2000 ofthe RX AIP 1202, and maps the combined signals into a number (Y) ofcorresponding channels for relay to the DPB 1010. Suitably, thecombining board 1210 maybe provisioned such that the mapping can beconfigured and/or readily changed for different applications and/orsystem arrangements. In one suitable embodiment, without limitation, thecombining board 1210 may operate to map 8 channels to the DPB 1010 from8 columns of the tapered elements 2000 in the RX AIP 1202. In anothersuitable embodiment, without limitation, the combining board 1210 mayoperate to map 8 channels to the DPB 1010 from 4 columns and 2 rows ofthe tapered elements 2000 in the RX AIP 1202, for example, without otherfurther significant changes to the system. In still another suitableembodiment, without limitation, the combining board 1210 may operate tomap 16 channels to the DPB 1010 from 4 columns and 4 rows of the taperedelements 2000 in the RX AIP 1202.

Suitably, the respective shields 1104, 1112, 1204 and 1212 interposedbetween respective boards of the aperture 1000 provides electromagneticshielding to and/or between the respective boards thereby protecting thesame against electromagnetic interference from neighboring and/or otherboards. In practice, the shields may be constructed of and/or formedfrom a metal and/or other like material which is suitably opaque to RFand/or other electromagnetic radiation. Further, the various heat sinkplates, e.g., such as heat sink plates 1302 and/or 1304, may provideadditional electromagnetic shielding to and/or between the variousboards of the aperture 1000.

FIGS. 86-88 illustrate various components of the cooling assembly 1300.Generally, the cooling assembly 1300 facilitates cooling of variouscomponents of the aperture 1000, e.g., such as amplifiers and/or otherheat generating electronic components on various boards within theaperture 1000.

With reference to FIG. 86 , the cooling assembly 1300 may include acentral duct 1310 extending between the intake and exhaust vents 1006-1and 1006-2. An air flow through the duct 1310 is suitably produced bythe array of fans 1306 which draws cooler exterior air into the duct1310 through the intake vent 1006-1 and exhaust hotter interior air outof the duct 1310 through the exhaust vent 1006-2. Suitably, the secondheat sink plate 1304 (shown separately in FIG. 88 ) may be in thermalcontact and/or communication with an underside the duct 1310 to withdrawand/or transfer heat out of the second heat sink plate 1304 via thecooling air flow generated in the duct 1310.

With reference to FIG. 87 , the first heat sink plates 1302 may likewisebe in thermal contact and/or communication with the central duct 1310,e.g., from respective sides thereof. As shown, each of the first heatsink plates 1302 may include a number of channels 1302-1 extendingtransversely to the duct 1310. Each channel suitably contains a heattransfer tube 1302-2. In practice, each tube 1302-2 may be sealed ateither end and contain a suitable thermally conductive liquid, e.g.,such as ammonium or the like. In some suitable embodiments, the tubes1302-2 may be made from a thermally conductive material or metal, e.g.,such a cooper (Cu). In practice, heat may be naturally conducted throughthe contained liquid and/or along the heat transfer tubes 1302-2 from adistal end away from the duct 1310 to a proximate end near the duct 1310without mechanical pumping of the liquid in the tubes 1302-2 or otherlike external forces being applied.

With reference now to FIG. 87 , one or more thermally conductive massesor heat sinks 1312 may be contained and/or housed within the duct 1310.For example, as shown, there are two such heat sinks 1312, however, inpractice there may be more or less. In the illustrated embodiments, eachheat sink 1312 may include an array of fins to increase a surface areaover which cooling air drawn through the duct 1310 flows. In somesuitable embodiments, the proximate end of each heat transfer tube1302-2 is in thermal contact and/or communication with at least one ofthe heat sinks 1312. In this way, heat is efficiently drawn from thetubes 1302-2 via the heat sinks 1312 and the cooling air flowing overthe same through the duct 1310.

In some suitable embodiments, each of the heat sink plates 1302 and 1304may have one or more surface formed and/or shape to fit around variousheat generating electronic components on adjected boards within the TXmodule stack 1100 and/or the RX module stack 1200 so as to be in closeor near thermal contact therewith. Suitably, the heat sink plates 1302and/or 1304 and/or the heat sinks 1312 may be made of a suitablethermally conductive material or metal, e.g., such as Al or Cu or thelike. Advantageously, the central location and/or positioning of thecooling assembly 1300 and/or central duct 1310 between the TX modulestack 1100 and the RX module stack 1200 promotes efficient coolingand/or heat conduction out of both stacks at the same time.

In some alternative embodiments, another liquid or passive or hybridcooling system may be used in place of the air cooling system 1300disclosed. In a suitable alternative embodiment, the air channel and/orcentral duct 1310 may be replaced by another suitable cooling mechanism,for example, which may include, without limitation, liquid cooling,passive cooling, or some hybrid combination of the two.

FIGS. 89 illustrates a partial section of an AIP in accordance with someembodiments disclosed herein, e.g., such as either one of the AIPs 1102or 1202. As shown, each AIP may include a number of electricallyconductive tapered elements 2000 that are mounted to and/or otherwisearranged on a board 3000, e.g., such as a printed circuit board (PCB) orother like carrier or suitable substrate. In practice, the plurality ofelements 2000 may be arranged in a matrix or two dimensional array ofrows and/or columns, for example, as more fully shown in FIG. 85 ,wherein adjacent pairs of the tapered elements 2000 define aperturepixels of a DSA. In the case of the TX AIP 1102, the matrix of taperedelements 2000 cooperate to transmit an OTA RF signal; and in the case ofthe RX AIP 1202, the matrix of tapered elements 2000 cooperate toreceive an OTA RF signal.

FIGS. 90-93 illustrate a perspective view, side view, top view andbottom view, respectively, of a tapered element 2000 in accordance withsome embodiments disclosed herein. As shown, the tapered element 2000includes a central hub 2002 extending along a central axis (CA) from ahub base 2004 to an apex 2006 of the tapered element 2000. The centralor longitudinal axis CA is perpendicular to the board 3000 and passesthrough the apex 2006. Suitably, when mounted to and/or arranged on theboard 3000 of the respective AIP, the hub base 2004 may be proximate tothe board 3000, while the apex 2006 is distal therefrom.

In some suitable embodiments, extending from the hub 2002 are aplurality of arms 2008. In the illustrated embodiment four such arms2008 are shown, however, in practice more or fewer arms may be used. Inparticular, each arm 2008 may include: a first portion 2008 a thatprojects the arm 2008 radially away from the central axis CA and/or hub2002; and a second portion 2008 b that projects the arm 2008longitudinally in a direction parallel or substantially parallel to thecentral axis CA, e.g., toward the board 3000 on which the taperedelement 2000 is arranged. As shown, the arms 2008 may be mutuallyorthogonal or substantially orthogonal to one another about the centralaxis, for example, as seen in FIG. 92 . In some nonlimiting illustrativeembodiments, the tapered element 2000 has S-fold rotational symmetryabout the central axis CA where S is the number of arms. Thus in theillustrative example each illustrative tapered element 2000 has fourarms and has four-fold rotational symmetry about the central axis CA.

With particular reference to FIG. 91 , one benefit of the design of thetapered element 2000 is that there are substantial open spaces 2011,i.e. regions of “missing” material 2011, between the arms 2008 and thecentral axis CA. This missing material improves the RF performance ofthe matrix of tapered elements 2000.

Typically, the downward extension of the central hub 2002 to the base2004 is not an electrically active element. For example, in someembodiments there may be no direct electrical connection made to the hubbase 2004 from or through the board 3000. Hence, in some embodiments(for example, as shown in FIG. 97 ), the central hub 2002 may omit thedownward extension of the hub base 2004. Said another way, in suchembodiments the central hub 2002 comprises only the joinder of thenumber of arms 2008. Omission of the downward extension of the centralhub also advantageously increases the area or volume of the open spaces2011.

As shown, the plurality of arms may include a first arm 2008 thatdefines a first plane in which both the first and second portions 2008 aand 2008 b of the first arm 2008 reside and a second arm 2008 thatdefines a second plane in which both the first and second portions 2008a and 2008 b of the second arm 2008 reside, the longitudinal axis CAbeing contained within both the first and second planes. Suitably, thefirst and second planes orthogonally intersect one another along thecentral axis CA. In some suitable embodiments, the plurality of armsincludes a third arm 2008 and a fourth arm 2008 arranged such that thefirst and second portions 2008 a and 2008 b of the third arm 2008 residein the first plane and the first and second portions 2008 a and 2008 bof the fourth arm 2008 reside in the second plane. That is to say, theplurality of arms may include a first arm 2008 and a second arm 2008,arranged such that the first portion 2008 a of the first arm 2008projects the first arm 2008 radially away from the central axis CA in afirst direction and the first portion 2008 a of the second arm 2008projects the second arm 2008 radially away from the central axis CA is asecond direction, the second direction being orthogonal or substantiallyorthogonal to the first direction. In some suitable embodiments, theplurality of arms includes a third arm 2008 and a fourth arm 2008arranged such that the first portion 2008 a of the third arm 2008projects the third arm 2008 radially away from the central axis CA in athird direction and the first portion 2008 a of the fourth arm 2008projects the fourth arm 2008 radially away from the central axis CA in afourth direction, the third direction being opposite the first directionand the fourth direction being opposite the second direction.

In some suitable embodiments, the tapered element 2000 may be a unitaryconstruction and/or singular continuous element. For example, inpractice, the taper element 2000 may be milled and/or otherwise formedfrom a single block or mass of a suitable metal, e.g., such as aluminum(Al) or an Al alloy, or another suitable electrically conductivematerial. In some suitable embodiments, the tapered elements 2000 may beinjection molded and/or otherwise formed. In some suitable embodiments,the tapered elements 2000 may be injection molded and/or otherwiseformed from a thermoplastic, thermosetting polymer or other likematerial that is generally not electrically conductive, and the somolded or otherwise formed material may be subsequently metalized and/orcoated with a layer or the like of suitable electrically conductivematerial.

With reference now to FIGS. 94 and 95 , in accordance with somealternative embodiments, the taper element 2000 may be formed from aplurality of separate parts suitably joined together. For example, asshown, the tapered element 2000 may include and/or be constructed from apair of separate parts 2000 a and 2000 b, each part including a pair ofopposing arms 2008 and a respective central portion which ultimatelycooperate to form the central hub 2002. In some suitable embodiments,each part 2000 a and 2000 b may be punch pressed (e.g., with a suitablyshaped die), cut or otherwise formed from a planar or substantiallyplanar sheet of suitable metal, e.g., such as Al or an Al alloy, oranother suitable electrically conductive material. Notably, constructingthe tapered elements 2000 in this manner can have a number of productionand/or manufacturing benefits, e.g., including but not limited to areduced manufacturing cost compared to milling and/or otherwise formingthe tapered elements 2000 as a unitary element.

As shown, the part 2000 a may include a slot 2010 a formed in thecentral hub region proximate the apex end thereof. Suitably, the slot2010 a extends from the apex 2006 in a direction of the hub base 2004 toand/or near a midpoint of the central hub 2002. Conversely, the part2000 b may include a slot 2010 b formed in the central hub regionproximate the base end thereof. Suitably, the slot 2010 b extends fromthe hub base 2004 in a direction of the apex 2006 to and/or near amidpoint of the central hub 2002. In practice, a completed taperedelement 2000 may be formed and/or constructed by interlocking the parts2000 a and 2000 b together such that the remaining portion (i.e., notincluding the slot 2010 a) of the central hub portion of part 2000 a isfit into the slot 2010 b, while the remaining portion (i.e., notincluding the slot 2010 b) of the central hub portion of part 2000 b isfit into the slot 2010 a. In some suitable embodiments, the respectiveslots 2010 a and 2010 b and the thicknesses of the respective parts 2000a and 2010 b are dimensioned to achieve a tight friction or force fitwhen the parts are interconnected as described above. In some suitableembodiments, the parts 2000 a and 2000 b may be otherwise secured to oneanother, e.g., via a suitable solder joint, weld or another suitablemetal joinery or other like joinery. In some suitable embodiments, theparts 2000 a and 2000 b may be held or otherwise secured relative to oneanother via respective connections to the board 3000 on which thetapered element 2000 is mounted and/or arranged.

Returning attention to FIG. 91 and with further reference to FIG. 96 ,the tapered elements 2000 may have a curvature or taper defined at theirapex 2006 and extending across opposing arms 2008 along an outerperimeter or edge 2020 thereof. For example, FIG. 96 diagrammaticallyshows a suitable curvature or taper of the edge 2020 of the taperedelement 2000. In some suitable embodiments, the curvature of the edge2020 may be defined by and/or given as y=Ae^(−bx)+C, where y is avariable representing a distance taken along the central axis CA, x is avariable representing a distance taken along an orthogonal radialdirection from the central axis CA, A is a non-zero constant ofproportionality, b is a non-zero exponential constant and C is aconstant. In some suitable embodiments, C may be zero or otherwiseomitted.

Returning attention to FIG. 89 , in some suitable embodiments, adjacentarms (e.g., arms 2008′ and 2008″) of adjacent tapered elements (e.g.,tapered elements 2000′ and 2000″) define an aperture pixel of the DSAtherebetween. Suitably, adjacent arms (e.g., arms 2008′ and 2008″) ofadjacent tapered elements (e.g., tapered elements 2000′ and 2000″) maybe electrically interconnected with one another via or through a balunor the like (not shown in FIG. 89 ). In some suitable embodiments, thebaluns may be mounted to and/or arranged on an under side of the board3000, i.e., on a side of the board 3000 opposite the tapered elements2000, or alternatively the baluns may be mounted to and/or arranged onrespective ones of the TX and/or RX conditioning boards 1106 and/or1206. In suitable embodiments, electrical connections from each taperedelement 2000 to their corresponding circuit (e.g., baluns or the like)may be made at the terminal ends of the arm portions 2008 b, i.e., theends of the arm portions 2008 b distal from apex 2006. Suitably,opposing pairs of adjacent tapered elements 2000 and/or their respectiveadjacent arms 2008 create and/or define the differential signaltherebetween. In some suitable embodiments, the hub base 2004 isprovided primarily for mechanical support of the tapered element 2000and/or mechanical connection of the tapered element 2000 to theunderlying structure (e.g., the board 3000). Accordingly, the hub base2004 may not have an electrical connection made directly thereto from orthrough the board 3000. In some suitable embodiments, the central hub2002 may not extend as far from the apex 206 as the arm portions 2008 band may fall some distance short of the board 3000 when the taperedelement 2000 is mounted thereto and/or thereon. Indeed, in some suitableembodiments, as shown in FIG. 97 for example, the end of the hub distalfrom the apex 2006 may terminate at a point which is flush orsubstantially flush with where the arm portions 2008 a cease extendingradially from the hub.

Advantageously, the central hub 2002 (for example, at or near the apex2006) provides a suitable location and/or structure for handling thetapered elements 2000 during manufacturing and/or assembly processes.For example, the central hub 2002 and/or apex 2006 provides a suitablelocation and/or structure which makes the tapered elements 2000conducive to manipulation by otherwise standard assembly line tools,e.g., such as pick and place machines.

In practice, as described herein, the various different functions of theaperture 1000 are distributed among multiple boards and/or components,e.g., such as the DPB 1010, the power supply boards 1108 and/or 1208,the TX and RX conditioning boards 1106 and/or 1206, the splitting board1110, the combining board 1210 and the TX and RX AIPs 1102 and 1202.Additionality, the foregoing boards and/or components are modularlyinterconnected within the aperture 1000. Accordingly, one or more of theforegoing boards and/or components may be selectively removed andreplaced without removing and replacing another one of the boards and/orcomponents. In this way, the aperture 1000 can be readily maintained ifone of the boards or components should fail, without having to replaceother functioning components and/or boards. Alternately, the aperture1000 can be readily upgraded and/or modified by replacing only selectedthe boards and/or components to effect the upgrade or modificationdesired without having to replace other components and/or boards notimpacted by the desired upgrade or modification.

In another illustrative example, a modular RF aperture 1000 comprises:an air interface sub-stack including an analog conditioning board 1106,1206 and an air interface plane (AIP) 1102, 1202 having a matrix oftapered elements 2000, wherein neighboring pairs of tapered elementswithin the matrix define aperture pixels and are configured to at leastone of receive or transmit over-the-air RF signals; a digitalpersonality board (DPB) 1010 including analog-to-digital converter (ADC)and/or digital-to-analog converter (DAC) components; a power supplyboard 1108 disposed between the air interface sub-stack and the DPB; afirst heat sink plate 1302 disposed between the air interface sub-stackand the power supply board; and a second heat sink plate 1304 disposedbetween the DPB and the power supply board.

In some embodiments, the modular RF aperture 1000 may further comprisean analog board 1110, 1210 disposed between the DPB 1010 and the secondheat sink plate 1304, the analog board configured to split and/orcombine analog signals received from the DPB and/or the air interfacesub stack.

In some embodiments of the modular RF aperture 1000, the air interfacesub-stack comprises a transmit (TX) air interface sub-stack 1106, 1102whose neighboring pairs of tapered elements are configured to transmitover-the-air RF signals and a receive (RX) air interface sub-stack 1206,1202 whose neighboring pairs of tapered elements are configured toreceive over-the-air RF signals, there being a gap spacing apart the TXair interface sub-stack and the RX air interface sub-stack. The modularRF aperture in this embodiment further includes a cooling mechanism 1310disposed in the gap spacing apart the TX air interface sub-stack and theRX air interface sub-stack, the cooling mechanism 1310 being in thermalcontact with the first heat sink plate 1302 and with the second heatsink plate 1304. In some nonlimiting illustrative embodiments, thecooling mechanism 1310 may comprise a central air duct, a liquid coolingmechanism, or a passive cooling mechanism.

In some embodiments, the modular RF aperture 1000 further comprises abase plate 1004 and a radome 1002. The air interface sub-stack, the DPB,the power supply board, the first heat sink plate and the second heatsink plate are disposed between the base plate and the radome, with theair interface sub-stack proximate to the radome and distal from the baseplate, and the DPB proximate to the base plate and distal from theradome.

The preferred embodiments have been illustrated and described.Obviously, modifications and alterations will occur to others uponreading and understanding the preceding detailed description. It isintended that the invention be construed as including all suchmodifications and alterations insofar as they come within the scope ofthe appended claims or the equivalents thereof.

1. A modular radio frequency (RF) aperture comprising: a first airinterface plane (AIP) including a first matrix of tapered elements,wherein neighboring pairs of tapered elements within the first matrixdefine aperture pixels and are configured to at least one of receive ortransmit over-the-air radio frequency (RF) signals; a first circuitboard electrically connected to the first AIP, the first circuit boardbeing selectively operative to at least one of condition or amplifyindividual signals at least one of provided to or received from eachaperture pixel of the first AIP; a second circuit board electricallyconnected to the first circuit board, the second circuit board beingselectively operative to at least one of: (i) receive a modulatedtransmit signal from a digital personality circuit board (DPB) anddivide the received modulated transmit signal into individual signalsfor each pixel of the first AIP; or (ii) combine individual receivedsignals from each pixel of the first AIP into a combined receive signaland provide the combined receive signal to the DPB; and a third circuitboard electrically connected to at least one of the first circuit board,the second circuit board, and the DPB, wherein the third circuit boardselectively provides electrical power to operate at least one of thefirst circuit board, the second circuit board, and DPB; wherein thefirst AIP, the first circuit board, the second circuit board, the thirdcircuit board, and the DPB are modularly interconnected such that anygiven one thereof may be selectively removed and replaced withoutremoving and replacing any other one thereof.
 2. The RF aperture ofclaim 1, wherein: the first AIP is a transmit AIP and neighboring pairsof tapered elements are configured to transmit over-the-air differentialRF signals; the first circuit board is a transmit conditioning boardselectively operative to at least one of condition or amplify individualsignals provided to each aperture pixel of the first AIP; and the secondcircuit board is a splitting board selectively operative to receive themodulated transmit signal from the DPB and divide the received modulatedtransmit signal into individual signals for each pixel of the first AIP;the RF aperture further comprising: a second air interface plane (AIP)which is a receive AIP, the second AIP including a second matrix oftapered elements, wherein neighboring pairs of tapered elements withinthe second matrix define aperture pixels and are configured to receiveover-the-air differential RF signals; a fourth circuit board which is areceive conditioning board, the fourth circuit board being electricallyconnected to the second AIP and selectively operative to at least one ofcondition or amplify individual signals received from each aperturepixel of the second AIP; and a fifth circuit board which is a combiningboard, the fifth circuit board being electrically connected to thefourth circuit board and selectively operative to combine individualreceived signals from each pixel of the second AIP into a combinedreceive signal and provide the combined receive signal to the DPB. 3.The RF aperture of claim 2, wherein the first and second AIPs, the firstcircuit board, the second circuit board, the third circuit board, thefourth circuit board, the fifth circuit board and the DPB are modularlyinterconnected such that any given one thereof may be selectivelyremoved and replaced without removing and replacing any other onethereof.
 4. The RF aperture of claim 2, wherein the third circuit boardis electrically connected to at least one of the fourth and fifthcircuit boards to selectively provide electrical power to operate atleast one of the fourth and fifth circuit boards.
 5. The RF aperture ofclaim 1, further comprising: baluns electrically connected betweenneighboring pairs of tapered elements within the first matrix.
 6. The RFaperture of claim 1, further comprising: a radome in which the firstAIP, the first circuit board, the second circuit board, the thirdcircuit board and the DPB are housed.
 7. The RF aperture of claim 6,wherein the radome is constructed from at least one of:polytetrafluoroethylene (PTFE), acrylonitrile butadiene styrene (ABS),thermoplastic elastomers (TPE), polycarbonate (PC), polybutyleneterephthalate (PBT), polypropylene (PP), nylon, and combinationsthereof.
 8. The RF aperture of claim 6, wherein the radome is injectionmodeled.
 9. The RF aperture of claim 6, wherein the radome istransparent to RF radiation.
 10. The RF aperture of claim 6, wherein theradome has a wall thickness in a range of between 3.0 millimeters (mm)to about 4.0 mm, inclusive.
 11. The RF aperture of claim 1, wherein thefirst AIP, the first circuit board, the second circuit board and thethird circuit board are arranged one over another in a first stack, suchthat the first circuit board is positioned between the first AIP and thethird circuit board, and the third circuit board is positioned betweenthe first circuit board and the second circuit board.
 12. The RFaperture of claim 11, further comprising: a base plate; one or morestandoffs which support the DPB on the base plate and space the DPB at adistance away from the base plate; and a radome connected to the baseplate; wherein said base plate and radome cooperate to form an interiorcavity in which the first AIP, the first circuit board, the secondcircuit board, the third circuit board and the DPB are housed.
 13. TheRF aperture of claim 12, further comprising: a sealing member arrangedbetween the radome and the base plate, the sealing member providing anair tight seal between the radome and the base plate.
 14. The RFaperture of claim 13, wherein the sealing member is one of a gasket oran o-ring which is squeezed between the radome and the base plate. 15.The RF aperture of claim 12, wherein the radome comprises: an exhaustvent in a first wall of the radome through which air is selectivelyflowed out of the cavity; and an intake vent in a second wall of theradome through which air is selectively flowed into the cavity.
 16. Amodular radio frequency (RF) aperture comprising: an air interfacesub-stack including an analog conditioning board and an air interfaceplane (AIP) having a matrix of tapered elements, wherein neighboringpairs of tapered elements within the matrix define aperture pixels andare configured to at least one of receive or transmit over-the-air RFsignals; a digital personality board (DPB) including analog-to-digitalconverter (ADC) and/or digital-to-analog converter (DAC) components; apower supply board disposed between the air interface sub-stack and theDPB; a first heat sink plate disposed between the air interfacesub-stack and the power supply board; and a second heat sink platedisposed between the DPB and the power supply board.
 17. The modular RFaperture of claim 16 further comprising: an analog board disposedbetween the DPB and the second heat sink plate, the analog boardconfigured to split and/or combine analog signals received from the DPBand/or the air interface sub-stack.
 18. The modular RF aperture of claim16 wherein: the air interface sub-stack comprises a transmit (TX) airinterface sub-stack whose neighboring pairs of tapered elements areconfigured to transmit over-the-air RF signals and a receive (RX) airinterface sub-stack whose neighboring pairs of tapered elements areconfigured to receive over-the-air RF signals, there being a gap spacingapart the TX air interface sub-stack and the RX air interface sub-stack;and the modular RF aperture further includes a cooling mechanismdisposed in the gap spacing apart the TX air interface sub-stack and theRX air interface sub-stack, the cooling mechanism being in thermalcontact with the first heat sink plate and with the second heat sinkplate.
 19. The modular RF aperture of claim 18 wherein the coolingmechanism comprises a central air duct, a liquid cooling mechanism, or apassive cooling mechanism.
 20. The modular RF aperture of claim 16further comprising: a base plate; and a radome; wherein the airinterface sub-stack, the DPB, the power supply board, the first heatsink plate and the second heat sink plate are disposed between the baseplate and the radome with the air interface sub-stack proximate to theradome and distal from the base plate and the DPB proximate to the baseplate and distal from the radome.